University
stringclasses 19
values | Text
stringlengths 458
20.7k
|
|---|---|
UWA
|
229
When the individual items of the plant are installed and commissioned to
start their operational service, maintenance service provider commissioning
officers supply details of the plant serial numbers and relevant locations
(substation circuit number and phase) to the asset management that updates
the relevant location details for the installed assets.
13.1.2. Lines and Cables
Asset management has the responsibility to ensure that all new transmission
lines and cables are registered in TLMS, with basic information copied into
M I MS to enable maintenance requirements to be set-up as per Section
13.1.4, and for the quality and accuracy of the recorded information.
The TLMS update starts at the point when the engineering design starts the
transmission line design and construction.
The responsible officer then inputs specification and order details,
line design and construction type details (length and number of structures,
structure details, electrical assembly and type and model of conductors and
insulators), and other technical characteristics of the line (eg rated load and
fault currents, rated and operating voltages).
When the line is constructed and all its poles are numbered, the responsible
officer enters line segment and pole number details from the site inspection
certificates available.
13.1.3. Secondary Equipment
Asset management has the responsibility to ensure that all new transmission
secondary equipment is registered in TPES, with basic information copied
|
UWA
|
230
into M I MS to enable maintenance requirements to be set-up as per Section
13.1.4, and for the quality and accuracy of the recorded information.
The TPES update starts at the point when procurement group places an
order for purchase of the equipment.
The responsible officer inputs specification and order details, type
and model of plant, and its technical characteristics (eg time and recording
function settings, rated and fault currents, operating voltages,
transformation ratios, etc).
When the plant is tested and delivered, and factory acceptance test
certificates are made available, the responsible officer enters plant serial
numbers for the relevant specification, item and order numbers.
When the individual assets are installed and commissioned to start their
operational service, maintenance service provider commissioning officers
supply details of their serial numbers and relevant locations (substation
circuit number and line denominators) to the asset management that updates
the relevant location details for the installed assets.
13.1.4. Asset Maintenance Requirements
Asset management has the responsibility to ensure that all transmission
assets added to the transmission network (lines, cables, primary and
secondary equipment) are promptly and correctly set-up in MIMS. That
allows for the definition of their maintenance requirements and planning
and execution of their required maintenance, and enables registration of all
asset-related activities.
|
UWA
|
231
These records need to indicate all assets that require particular preventive
activities (warranty control, inspections, checks and maintenance) by
entering the necessary requirements from the maintenance policy manual.
The update starts when an asset is reported as operational and established in
TPMS, T L MS or TPES. The responsible officers will assess details of the
installed asset and identify it in the maintenance policy manual. If it differs
from anything in the current list, a request is issued to the responsible
function to add it to the list and determine its new schedules with the
maintenance service provider.
Once all maintenance requirements information is obtained and determined,
it is programmed and entered into MIMS. That includes a number of
maintenance requirements, their maintenance levels and frequencies, links
to relevant standard jobs, details of warranty requirements, and
maintenance costs.
The entered requirements information is used by the maintenance service
provider work schedulers to plan the required works, coordinate with
system operations through the use of outage management procedures, and
to submit to the provider maintenance crews for the work execution.
13.1.5. Asset Ratings
Asset management is responsible for ensuring all new transmission current-
carrying assets (lines, cables, circuit breakers, current transformers,
busbars, transformers and connections), registered in T P MS and TLMS, are
defined in TRIS with their current rating characteristics, and for the quality
and accuracy of the recorded information.
|
UWA
|
232
The update starts when an asset is recorded as operational in T P MS and
TLMS. The ratings officer will assess all normal and fault ratings
information available about lines, cables and plant, and update the relevant
information in the database.
This would include thermal and fault currents, overloading and time
characteristics from the results of its type and routine tests, details of the
ancillary components used to join the plant, its conductor and winding
details, and various climatic loading curves.
Asset management will then arrange for or perform necessary rating
calculation programmes to determine the load and fault current rating
capabilities of the asset in its particular location; taking into the account
local climatic (temperature variations, wind), load (load profiles) and soil
conditions (soil type, flooding).
13.1.6. Asset Geographical Locations
Asset management is responsible for ensuring geographical location
information for new transmission major assets (lines, cables and
substations) registered in T P MS and T L MS is recorded in TLGIS, and for
the quality and accuracy of the recorded information.
The TLGIS update starts at the point when a project is approved to establish
a new substation or construct new line or cable. The responsible officer
inputs necessary project and basic location details, which arelater updated
as more information from the site measurement become available.
|
UWA
|
234
- success of repair work (cancelled, completed or partially done);
- outstanding work required.
That will enable analysis of the maintenance work done through production
of various reports explained in Chapter 14, and it will assist in identification
of incidents.
That is in turn used to determine incident characteristics to identify which
incidents were faults and failures of the transmission assets, as to further
analyse the asset performance:
13.2.2. Network Outages
All network outages and the requirements for future outages are recorded
by system operations personnel in the N O IW database explained in Section
11.2.4 to enable coordination, planning and safe execution of the required
maintenance and other works on the transmission network assets.
The maintenance service providers apply for an outage via two methods to
record their requests for required circuit outages into N O IW database:
- via interface link from MIMS to NOIW system where the interface
program is run daily to create, update and delete the N O IW and M I MS
records (generally preferable method);
- manually in an emergency where a relevant form is sent to the SO who
then manually enters the required information into NOIW.
|
UWA
|
235
It is the role of the SO controllers and maintenance service provider work
schedulers to synchronise both databases as they become "unsynchronised",
when daily changes to the work and the outage requirements arise.
The work schedulers, who operate and run the maintenance work database,
have the final responsibility in validating and monitoring all asset-based
work orders, where the SO controllers have the ability to globally move
individual and multiple switching work orders for required outages in the
N O IW database.
It must be stressed that at all times the system operations personnel and the
work schedulers need to communicate with each other to coordinate
outages, as this communication process is fundamental element in ensuring
that the maintenance work and related outages procedure is successful.
13.2.3. System Operation Disturbances
Often a disturbance occurs in the transmission network that causes an
outage of a part of the transmission network, which becomes non-
operational, with or without loss of supply to any customer.
That outage might happen suddenly without warning due to some other
faults causing protection to isolate that part of the network, or an outage will
have to be arranged immediately as the disturbance poses some kind of a
threat to the transmission network (public safety, plant integrity, etc).
All such network disturbances, where a part of the transmission network has
become non-operational, need to be recorded by the system operations
|
UWA
|
236
control centre officers in the System Operation Disturbance database with
all the necessary details as defined in Section 11.2.3.
13.2.4. Protection Operations
Every time a disturbance occurs in the transmission network that requires a
protective action for that relevant part of the network, one or more
protection relays will operate.
These immediately localise the source of the disturbance and limit the
impact of that system disturbance as quickly and as much as possible on the
overall operation of the transmission network.
All such network incidents, where a part of the network protection
equipment has been called into operation, need to be investigated by asset
management. The results are then recorded with all the necessary details in
the TPES database with information about the appropriateness of the relay
operation and subsequent action taken.
13.2.5. Primary Plant A llocations
Asset management is responsible for ensuring all the transmission primary
plant that are currently not used in the system (eg units on order, in transit,
in repairs, on testing or in spares custody stores) is properly accounted for
and registered in the TPAS database. It is also responsible for the quality
and accuracy of the recorded information.
The update starts when the new plant is ordered, or when an operational
unit already recorded in T P MS is released from service on site.
|
UWA
|
237
The responsible officer will obtain all necessary details from the purchasing
officer for the new equipment or use details from the received Primary
Plant Return Form (PPRF) received upon release from the service of an
existing equipment to make a record of its status and location.
Appropriate documentation is then sent out to the relevant parties to advise
them of the necessary details about the asset for their work, or about
necessary action they need to perform (allocation sheet, repair request,
testing request, transport request, disposal notice, etc).
13.2.6. Secondary Equipment Allocations
Asset management is responsible for ensuring all the transmission
secondary equipment currently not used in the system, eg units on order, in
transit, in repairs, on testing and in stores are properly accounted for and
registered in TPES, and for the quality and accuracy of the recorded
information.
The update starts when the new secondary equipment is ordered or when an
operational unit already recorded in TPES is released from service on site.
The responsible officer will obtain all the necessary details from the
purchasing officer for the new equipment or use details from the received
Relay Return Form (RRF) received upon release from the service of an
existing equipment to make a record of its status and location.
Appropriate documentation is then sent out to the relevant parties to advise
them of the necessary details about the asset for their work, or about
|
UWA
|
238
necessary action they need to perform (allocation sheet, repair request,
testing request, transport request, disposal notice, etc).
13.2.7. Network Development Plans
It is the responsibility of network planning to record all development
activities for the future network requirements dealing with transmission
network assets in the Network Development Plans Summary database as
defined in Section 11.2.5.
They need to subsequently make any changes and adjustments to those
records promptly, as their planning work progresses, and corrections in
targeted assets or timing of the works become necessary.
13.3. Recording of Asset Failures
Asset management is responsible for ensuring failures for all assets
currently used in the transmission network are properly accounted for and
registered in T P MS (for primary plant), T L MS (for lines and cables), and
TPES for secondary equipment, and for the quality and accuracy of the
recorded information.
The failure records are based on information produced by a number of
reports on primary plant and line activities from various databases
explained in Chapter 11.
Transmission asset failures are recorded to enable the analysis of asset
faults and failures, and type and history of those defects. It is also necessary
|
UWA
|
239
to understand the mechanism of the defects, so it is important to enter all
data in a correct and a consistent manner.
13.3.1. Event Definition and Data Requirements
There is the need to define events before the actual event recordings are
effected, as is presented in the two defect definitions below:
A- Fault is the state of an item characterised by its inability to perform a
required function, which can be due to the event of failure of the item itself
(Trip) or to requirement for the forced outage to deal with the item
(Emergency). This excludes scheduled and planned corrective outages.
B- Defect is an imperfection in the state of an item, which increases the
probability of failure of itself or another item, but can be addressed at a
later time through scheduling of planned corrective outages.
There is also a need to define data to be captured before the actual event
recordings can be done, as is presented below:
- Line, line segment or circuit identifier;
- Date of incident;
- Component identifier;
- Comments on failure, possible cause, deterioration rate and trend;
- Consequence;
- Inspection procedure (global, routine, detailed);
- Technique used (visual, diagnostic, analysing samples);
- Comments on work done or to be done, conclusions.
|
UWA
|
245
3. The third character will identify the cause type:
Third Character Type of Cause
L Lightning
W Adverse Weather (wind, ice, galloping)
N Adverse Nature (tree, vegetation)
F Pole Top Fire (pollution)
H Human Intervention (crane, vandalism, sabotage
etc)
E Equipment (design, material, aging)
O Other (but known)
A typical record would look like this,FSF, meaning a forced outage (trip of
relays involved) of a wooden pole that had a pole top fire.
13.3.3.3. TPES
The TPES database is used to record failures of the secondary equipment
according to the appropriateness of the relay operations when called or not
into the operation.
There are three distinctive relay failure modes that need to be recorded by
using the guidelines shown below:
- when called to action but failed to operate;
- when called to action but operate wrongly or partially;
- when not called to action but operated on its own accord.
Asset management investigates all such incidents, and the investigation
report findings are also entered into TPES database against the relevant
relays for future reporting of the secondary equipment performance index.
|
UWA
|
248
They assess asset performance indicators by reviewing statistical reports on
asset performance, ie asset failures, emergencies and forced outages.
The main issues to be discussed and evaluated are:
frequency and location of failures,
recurrence of failures,
assessment of asset condition,
new environmental and regulatory requirements,
safety of employees,
safety of public,
safety of adj acent plant,
ability to manage the process (manage rather than be failure driven).
A summary of findings is produced as a result of the above discussion, and
then cross-referenced to and coordinated with the findings and the
recommendations in Section 13.4.1.
13.4.3. Asset Maintenance Plan
The relevant staff from asset management and asset maintenance service
providers conduct regular monthly meetings to assess the execution and
appropriateness of the current asset maintenance plan over the previous
period, and to determine the adequacy of the plan for the next period.
They also discuss summary of asset maintenance and asset performance
reviews from Sections 13.4.1 and 13.4.2, to assess the impact of the
recommended changes to the asset maintenance plans and to the on-going
and future scheduled maintenance activities.
|
UWA
|
251
13.4.7. Asset Management Plan
The Plan is reviewed in full by asset management at least annually to check
the mutual impacts of network development plan and asset management
plan recent changes.
This is also necessary to confirm the status of the work in progress, update
its contents with the results of various other reviews throughout the year
and to produce its updated version.
A procedure is used to establish assets that will require some work in the
future and needs to be included in the Asset Management Plan is shown in
the process flow chart in Fig. 13.1.
Asset management develops on an annual basis a 'first cut' list of assets
considered to be a possible candidate for the update of their maintenance
documentation or for some work on them (eg modification, refurbishment
or replacement) from the Asset Directory.
The assets are identified on the basis of analysing plant reliability, age,
failure rates, and their assessed condition, and put into a list called Assets
Under Review.
The items on the initial list are then subjected to a high level analysis. The
analysis covers the impact of new developments and planned upgrades, and
assess how critical the asset position is in the system, its current condition,
and likely cost and benefits of asset renewal options.
An investigation will be initiated to assist in determining the future
preferred action if appropriate.
|
UWA
|
253
Information should be gathered regularly from other electricity authorities
and industry forums and used to assist in assessments to arrive at the
decision to refurbish or replace.
This may lead to a refinement in decisions when the 'first cut' list is
prepared.
The initial list is reviewed annually in conjunction with network planning
and system operations before long-term capital budget projections are set
up in the company with the asset owner.
The refined 'first cut' list is a basis for the creation of the Asset Future
Projects portfolio, indicating expected actions and time frames, and
presenting estimates for the annual review of the capital budget.
Asset management prepares detailed technical and financial business cases
as required, and presents them to the company's management through the
proper procedure for requesting maintenance and capital funds.
The approved proposals are then handed over to project management
for the project execution according to the existing project management
practice.
Asset management continues its involvement with the approved projects as
a sponsor until the projects are completed, or if the above performance and
planning reviews identify the need for their possible deletions or for
updates in their scope of work and/or timing.
|
UWA
|
254
13.4.8. Asset Management Process Performance
Asset management needs to measure the success of the asset management
process by assessing is it meeting the set-up performance targets for plant
and network performance by reviewing the network performance indicators.
A number of indicators are used to objectively measure outcomes of the
process, and the main ones are listed below:
number and assessment rating of site inspections;
percentage of overall plant failures;
number of explosive failures;
number of incidents with conductor on ground after fault;
line failures rate per 100km of lines;
percentage of fault outages;
ratio of preventive to corrective maintenance work.
The results are distributed on a monthly basis to all other business functions,
and presented and reviewed through an annual workshop amongst the
representatives of the functions.
13.4.9. Asset Management Process
Asset management needs to ensure that the adopted model and its asset
management process are proper and applicable for the current business, and
therefore needs to subjected to the relevant audit and review exercises,
carried out by internal and external specialists providing such audit services.
|
UWA
|
256
14. REQUIRED REPORTS
There are a number of asset incident reports that need to be initially
prepared from basic asset databases and analysed on a regular basis to
achieve the continuous review and monitoring of performance and
condition of the assets.
The results of these initial reports are then examined, catalogued, and used
for updating a number of other asset performance databases.
The outcomes of those asset incident reports and other reports from the
referred performance databases are then used to detect and highlight assets
with deteriorating maintenance, operational or financial performances and
decay in their overall condition.
The first level reviews and subsequent detailed assessments, where found
necessary for the highlighted asset, will give an initial indication of any
necessary action or show if further, and more comprehensive, investigations
and assessments are warranted.
A business case analysis outcome will determine and recommend necessary
works for the assets deemed to require a more detailed review. The
business case outcome will also decide which responsible groups are
required for the recommended works and in what timeframes.
The sequence of the reporting, and reviewing of the above reports, are
presented in Fig. 14.1.
|
UWA
|
258
14.1. Asset Incident Reports
14.1.1. Corrective Maintenance Works
This report is produced monthly to monitor and review all maintenance
work done on assets other than planned preventive maintenance work as
defined by the asset maintenance policy and criteria document, ie outside
asset preventive maintenance regimes (refer to Section 13.3.2.1).
All corrective maintenance work listed on the report is analysed to check
which activities were performed during the preventive work, and which
were not.
Only those activities performed as part of the preventive work are not
counted as plant failures, where all other activities performed on their own,
ie not during the preventive regime maintenance work, are deemed failures.
They will then be entered into the failure database following the relevant
process and the coding as described in Section 13.3.
The report contains the following details to be used to analyse regular
performance of assets, to calculate the number of plant failures, and to
produce other performance statistics:
• facility denominator (substation, circuit, phase, line name, pole number);
• type of asset (manufacturer name and asset type description);
• description of fault;
• type of fault;
• date of incident;
• asset serial number;
|
UWA
|
259
• work order number;
• repair crew identification code;
• corrective action taken;
• date of repair;
• cost of repair;
• corrective action type;
• success of repair work;
• any outstanding work to be done at a later stage.
This specified review of the corrective maintenance activity involves more
than just checking of the details of each of the individual defect.
It also includes all previous maintenance work done on the selected plant
with a defect, for the reason of checking the following:
• has that type of repair occurred before, and how many times;
• was that repair done before or after preventive maintenance, and how far
away from it;
• what type of repair procedures was applied in the past (same or
different);
• was the repair performed by the same or different service provider or the
crew.
That should provide enough initial information to conclude if that defect
was an isolated occurrence, or if a trend is emerging for that particular unit,
or the whole plant family that needs to be further investigated.
|
UWA
|
260
14.1.2. Protection Equipment Operations
This report is produced fortnightly from the TPES protection relay
operation records to identify and review all network incidents that have
caused the protection relays to operate (refer to Section 13.3.2.2).
All relay operation records listed in the report are analysed to find out the
activities that were caused by the plant-related incidents.
Only the relay operations due to the plant failures are counted, and are
deemed failures. All other records due to other reasons are not counted.
The records are then entered into the failure database following the relevant
process and the coding as described in Section 13.3.
The report contains the following details that are used to analyse regular
performance of assets, to calculate the number of plant failures, and to
produce other performance statistical data explained in Section 14.2.3:
• type of asset;
• facility denominator (substation, circuit, phase, line name, pole number);
• date and time of incident;
• description of fault;
• fault type;
• cause and circumstances of the fault;
• action taken.
|
UWA
|
262
14.2. Asset Performance Reports
These reports are prepared monthly using data in the TPMS, TLMS and
TPES databases, and are used to perform a detailed analysis of asset
performance.
The outcomes will highlight all the assets and their equipment types
that represent the main contributors to the obtained asset failure rates that
will require further work to determine reasons for their poor performance.
Each of these reports covers a particular asset, ie switchgear, lines and
protection relays. The lists are further expanded to identify the specific
equipment types and their locations to easily highlight the ones with the
most recorded number of failures.
The failures of the same or similar models are aggregated, and then sorted
out by voltage levels to make it easier to highlight problematic equipment
items or types from the produced list.
The review of that information is used to determine if a further analysis of
asset failures for asset types represented in these failures is warranted.
This review also assists in making an initial decision if the asset should be:
• considered for some action in the future (proceed to seekbenefits for its
repair, refurbishment, modification or replacement);
• recommended for further investigation of its maintenance regime and
servicing;
|
UWA
|
265
The report highlights the deterioration of relay performances, and prompts
an analysis and identification of the especially problematic relay types by
identifying incidents where relays did not perform their expected duty, or
malfunctioned when not called into operation.
The report findings are also cross-referenced to other asset activities in
progress, as given in the Asset Management Plan.
The report indicates the items already under control, as some action
is due or it is in progress, thus saving time by avoiding investigation of the
same problems again, and also ensuring that no problem is neglected or left
undetected.
14.2.4. Asset Failures Summary
This report is produced at least annually to highlight all equipment types
that fared prominently throughout their total years in service with regard to
the defects and failures in their operation.
The report contains the following information:
- Specification, item and purchase order numbers, and order date;
- Voltage level, manufacturer and manufacturing type;
- Equipment type;
- Number of total failures recorded, and defects year-to-date;
- Average age;
- Number in use.
|
UWA
|
267
15. REQUIRED OUTPUT DOCUMENTATION
One of the main features of the developed integrated model is the need to
have a range of specified output documentation.
The output documentation is used in the defined asset management process
to collate outcomes of initial procedures and to present the outcome
information in a format that is easy to use. It further defines procedures that
will ensure action on those outcomes by the required business functions.
15.1 Asset Management Plan
All information generated from the asset management processes is collated
and issued in a document called an Asset Management Plan.
The Plan deals only with the ongoing performance of the assets
currently installed in the system. The Plan needs to be updated with
relevant changes from other areas that have impact on the Plan.
The Asset Management Plan is the end result of the involvement of a
number of responsible business functions that perform associated asset
management procedures.
Its purpose is to identify assets that need some action in the future and to
define what that action is, or the additional information needed to assess the
condition of the asset to estimate its remaining useful and safe operational
life before some work is required.
|
UWA
|
268
The plan contains details of all current and future approved or planned asset
renewal activities based on the importance that the assets represent to the
operations of the transmission network and with regard to the planned
enhancements of the network.
Therefore, the plan represents an expected long-term strategy for the
transmission network assets currently in service.
The objectives of the Asset Management Plan are to ensure that:
• assets with suspected performance, high maintenance costs and poor
condition are identified, recorded, and have a critical level assigned;
• the activities are in place to investigate and review the above assets;
• business case analysis is performed on the relevant identified assets to
determine best outcome and required action for improvement of the
suspected assets and to mitigate the impact of their defects or failures on
the performance of the network;
• long-term plans are put in place to implement the outcomes and
recommended actions from the above business cases;
• input to the company's long-term business plans to reflect the necessary
maintenance and capital expenditures to additionally maintain, renew
and replace assets as their life is expended;
• the safety of employees, customers and the public is protected;
• environmental impact is acceptable;
• long-term viability of the business is ensured;
• shareholder value is increased.
|
UWA
|
269
The Asset Management Plan covers the total population of the transmission
network assets, ie all transmission primary and secondary equipment as
presented in the Asset Directory.
The performance of the total population is reviewed monthly, through an
application of a range of regular reports, and annually, when the assets in the
Asset Directory are subjected to a number of high level reviews of their
service performance through analysis of a number of annual reports.
The relevant reports used for these reviews were presented in Chapter 14.
The outcome of those reviews is contained in a list of assets with a possibly
suspected performance that will warrant a closer scrutiny, and is called
Assets Under Review.
15.1.1. Assets Under Review
Assets Under Review is a list of equipment that has been determined from
the initial reviews of the Asset Directory to warrant more detailed analysis.
That initial review may lead to one of three basic outcomes:
1. Performance is still acceptable, or other plans render it satisfactory for
the time being, so no further action is needed;
2. Further information is needed about the plant in question to reach a
proper conclusion and prepare necessary recommendations on its future.
The plant item is then referred for more investigation work, and is listed
in the Asset Investigations part;
|
UWA
|
270
3. The plant is assessed that it will definitely need some action in a near or
later future, and is included in the Asset Future Projects part. The listed
projects are grouped into the time frames of 5 years, 10 years, 15 years,
and over 15 years.
15.1.2. Asset Investigations
Before or during a more detailed assessment of performances from the
items in the Assets Under Review list, additional information or data may
be found to be necessary prior to making any reasonable decision about the
identified suspected asset.
Records about investigations and their status are in the Asset Investigations.
This can include a number of special inspections, tests and measurements;
seeking input from the manufacturer and other similar companies, and may
also include various trials and joint research projects with other authorities,
companies, universities and manufacturers.
Outcomes of such investigations can be split into two main groups:
1. No additional work will be required for the asset as:
(a) the relevant units can be relocated to less important or demanding
locations in the network; or
(b)no action at all as asset failures will be sufficiently catered for by the
existing generic or special contingency plans for a specified period;
2. The assets in service will require some additional action earlier or later
into the future, and should be added to the list of Asset Future Projects. A
|
UWA
|
271
detailed business case analysis process will apply in due course to decide
their final fate (eg. refurbishment, modification, etc).
15.1.3. Update of Documentation
The results of an asset investigation or a business case analysis could often
point out that the best way to solve the identified problems would be
through an update of its handling in the maintenance process without any
significant physical work required on the asset.
That could include altering the asset maintenance approach such as
maintenance policy requirements, maintenance servicing details or
maintenance access instructions, which is then registered through the
update of its relevant documentation.
Another method would be through altering one of the existing generic
contingency plans, including varying the current policy of holding
necessary spares, or an option to develop a special contingency plan.
15.1.4. Asset Future Projects
The Asset Future Projects list represents the potential work necessary to
address the plant renewal options.
The following range of timeframes are considered:
• 0-5 years - Plant that will be considered for action within the next five
years, with the recommended type of action and timing presented with
|
UWA
|
272
as many details as possible, including type and exact estimates of the
required funds;
• 6-10 years - Plant that will need to be considered for action in five to ten
years, with the estimated type of recommended action and its timing,
and a reasonable estimate of funds that would be required;
• 11-15 years - Plant to be considered for action between 10 and 15 years,
with a very rough description of the recommended type of action and
timing, with a broad estimate of action and funds that could be required;
• over 15 years - Plant to be considered for action after 15 years in
service, with a basic description of the recommended type of action, its
timing and possible cost estimates for the work.
The projects from this potential work program are subjected to a detailed
business case analysis when they are due according to their anticipated
timeframe, or earlier, if the performance of the asset in question
deteriorates, to determine if and when the project should actually proceed.
When the outcome of the business case is positive for a certain type of
action, the recommended action and the timing proposal will be prepared
and submitted through a standard company procedure for obtaining capital
or maintenance funds.
When the approval for the recommended works and required funds has
been received, the relevant maintenance or capital project will be added to
the list of Asset Planned Projects.
|
UWA
|
274
The plan also serves another important purpose, that is to achieve a proper
coordination and optimisation of all maintenance and capital works through
the model defined reviews, by having the full visibility of all maintenance
works.
That will avoid a situation where several different maintenance and capital
works are being planned or done on the same asset by various business
functions in the same or similar period.
It also provides a good basis for the coordination and optimisation in regard
to capital planned works that are contained in the Asset Management Plan
and the Network Development Plans.
The programme of all required asset maintenance works contained in the
asset maintenance plan is divided into the respective maintenance category
works as per definitions in Section 7.3.7, which are summarised in the
following:
• Preventive maintenance work;
• Corrective maintenance work;
• Major works (a major asset works for which maintenance operating
fund approvals have been obtained).
The formulation of the plan is covered in Section 7.3.8, with the subsequent
maintenance budget proposals being prepared by following Section 7.3.9.
|
UWA
|
277
The responsible centre code used for the account codes in work orders is
different for the primary and the secondary assets to enable a proper
maintenance cost analysis.
Separate activity codes are used to form an account code in work orders for
the maintenance work activities.
It is also required to use codes for the individual maintenance service
providers in a work order to enable the analysis of the service providers
involvement.
15.3 Business Case Studies
The regular analysis and review of asset performance leads to the initial list
of assets with a suspected condition, as explained in Chapter 13.
That list is then further subjected to another high-level analysis and
investigation, where required, to determine if any action is required in the
future, and if the asset needs to be included in one of the Asset
Management Plan lists defined in Section 15.1.
This further review leads to the asset being included in the Asset Future
Projects portfolio, which indicates expected actions and required action
time frames with rough cost estimates as a basis for the long-term capital
and maintenance budget forecasts.
When the right time comes for action on a particular asset project from the
Asset Future Projects portfolio, a detailed technical and financial business
|
UWA
|
278
case needs to be prepared. That is done according to the Asset Business
Analysis Manual following the procedures explained in Chapters 9 and 13.
The final proposal is presented to the management through the company's
standard capital and large maintenance project approval procedure.
The possible outcomes of the asset business case analysis are presented
with a recommendation to pursue a course of action selected from the
options described in Section 9.5.
Briefly, the recommendations may propose that no additional work will be
required on the asset itself, but with some other action, or that the asset will
require some action, and a recommendation for approval of capital or
maintenance funds is made.
After the approval is obtained, the recommended project is handed over to
project management for its execution, who will provide regular updates on
its course to asset management throughout the project works.
Th relevant project will also be moved from the Asset Future Projects to the
Asset Planned Projects part of the Asset Management Plan.
An example of the actually prepared, approved and completed business
case for the replacement of 132kV circuit breakers is presented in Chapter
16, with a discussion about the whole procedure.
|
UWA
|
280
failed transformer is removed from the substation and a permanent spare
unit is installed in its place;
3. The cable contingency plan for the metropolitan inner city area deals
with the inner city substations that might be left without proper power
supply in the event of the failure of some major inner city cables
amongst those substations.
The plans will enable the quick erection of an overhead line between
any of the affected substations through the nominated city streets to
bypass the failed cable, thus restoring the full power supply to the
affected central business district.
There could also be a requirement for other special contingency plans for
catastrophic events considered well beyond normal operating risks to cover
such events in the specific periods of a high load growth before other
contingencies are made in the generic contingency plans.
A preparation of such plans is the responsibility of the network
development function.
That could typically include events such as:
> Loss of a whole terminal substation (eg. if light plane crashes);
> Expecting unusual storms that can cause widespread damage (eg.
cyclone);
> Rare system events (eg cascade tripping of 330kV lines caused by a high
unusual humidity);
> Coincident events (eg multiple bushfires in a very dry summer affecting
multiple major lines).
|
UWA
|
281
16. PRESENTATION OF AN APPROVED BUSINESS CASE & ITS
DISCUSSION
The thesis has explained and formulated the relevant documentation and
procedures for the preparation and review of business case on a non
performing asset that is necessary for a full implementation and running of
the model and its process.
That has been applied to a real case, and the details of the review are given
in the following Sections.
16.1. Introduction
The company purchased a total of 65 units of the circuit breaker under two
specifications, 12/MU, Items 1&1A (27 units, 23 in 1963 and 4 in 1967/8)
and 10/K, Item 1 (38 units in 1967).
There were 30 units still in service (46 % ), 12 units of Specification
12/MU (44 %) and 18 units of Specification 10/K (48 % ).
Major problems occurred associated with their high-pressure hydraulic
systems, some requiring up to six repairs per year, causing frequent plant
outages and incurring high repair costs on top of their expensive regular
preventive maintenance work.
These problems were not been resolved despite a number of initiatives and
investigations, involving several manufacturers and own staff.
|
UWA
|
282
Due to the design of their hydraulic system that uses high gas pressure to
operate the unit, most of the components are worn out.
A number of parts were dismantled and resealed with new gaskets,
but the gas and oil leaks were repeatedly occurring within a short period.
Some of these units were soon to be replaced through other approved
network development projects due to the fault level increase, but there were
no plans for the replacement of fifteen units in any of the future network
development projects.
Therefore, there was the need to assess the remaining fifteen units and
prepare a business case for the possible improvement of their performance
or for their replacement by using the developed business case analysis and
its risk assessment matrix from Chapter 9.
16.2. Calculation of Business Case Component Risk Factors
The relevant business components had their risk factors calculated to enable
determination of the risk ranking as per Section 9.2:
16.2.1. Age
The units are 31 to 35 years old. The expected operating life for that type of
equipment is 40-45 years, and their risk factor is therefore rated at three.
|
UWA
|
283
16.2.2. Frequency of Failures
The above units have recorded a high number of failures causing outages
for their repair, diverting resources from other planned preventive works.
The summation of these failures is shown below:
6 units at Western Terminal (WT) -34 failures over the last five years;
6 units at East Perth (EP) -12 failures over the last five years;
2 units at Merredin (MER) - 4 failures over the two last year (no
records of previous performance);
1 unit at Bunbury (BU) -no records of previous performance
The average failure rate is approximately 50/15/5=0.66, and the risk factor
is therefore rated at five.
16.2.3. Condition
The condition of these units is not satisfactory, with frequent gas and
hydraulic oil leaks through various seals and repetitive breakdowns of their
hydraulic pumps and compressors.
That extensive and detailed repairs and reconditioning of the pumps
and seals in-house had only a moderate success, as the units developed
further leaks and faults soon after the repairs.
Many worn parts are subjected to high hydraulic gas and oil pressures
during the breaker normal and fault operations (300 bars).
|
UWA
|
284
That is causing high corrective maintenance costs assessed at $424K for the
next 12 years. The comparison to the expected cost of $700K for preventive
maintenance gives the ratio in the range of 50-100%, and therefore the risk
factor is rated at four.
16.2.4. Environmental & Regulatory Requirements
The possible consequence of their failures could be a release of hydraulic
mediums, such as gas and oil, into the atmosphere and the surrounding soil.
That is not environmentally acceptable as there are regulatory requirements
as well as certain limitations on such leaks, to which the company has
agreed with various government departments and national associations to
adhere to. Therefore, the risk factor is rated at three.
16.2.5. Maintenance Costs
16.2.5.1. Preventive Maintenance Costs
The above units currently in service require regular preventive
maintenance, where alternating lower and higher service levels (A and B)
are applied every two and four years respectively.
The costs of performing these levels of maintenance are:
Level A-Check Maintenance $ 4,770;
Level B-Full Maintenance $ 11,600.
|
UWA
|
285
The preventive maintenance work cost over the next 12 years is estimated
at $48,110 per circuit breaker, or $725,000 for all units.
16.2.5.2. Corrective Maintenance Costs
The above units have a high repair rate, with the cost of corrective
maintenance between 1993 and 1998 totalling $177,000 in addition to their
preventive maintenance costs.
It is estimated that similar expenditure will continue to occur over the next
12 years, and will cost an additional $424,000.
16.2.5.3. Summary of Maintenance Costs
The total maintenance costs for the 15 units over 12 years will be $1.2M
with a figure of $6,600 per unit per year.
The comparison to the expected replacement cost of $82K for a new unit
gives the ratio of 8%, and therefore the risk factor is rated at five.
16.2.6. Replacement Costs
The proposal is to replace the defective units with new gas insulated units
requiring little maintenance (checks every 12 years) and a cost of
approximately $82,000 per unit to purchase, install and commission.
The difference between the replacement and continuous operation is greater
than 50%, and therefore the risk factor is rated at five.
|
UWA
|
286
The new units will also have a higher fault current rating, and will satisfy
long-term planning requirements for the respective substation sites.
16.2.7. Spare Parts Availability
The units in question are of an old design, and no original spare parts are
available due to the fact that the original manufacturer ceased to exist.
Some parts are being made temporarily available by refurbishment of
the surplus units replaced from other sites as part of other development
projects. Unfortunately these parts are worn out, and even the refurbished
ones are not in a good enough condition to guarantee the long-term secure
operation of the units using the refurbished parts.
The main part spares are not available from the original manufacturer, and
due to high costs to re-manufacture them on an individual basis, the risk
factor is rated at five.
16.2.8. Competency of Employees
The skills to repair these units or to refurbish their parts exist within some
of the company's substation maintenance service crews, and the risk factor
is rated at two.
Unfortunately, their use is limited due to lack of parts and worn
components as explained in Section 16.2.7.
16.2.9. Availability and Cost of Refurbishment Services
This area is considered to be of limited use, due to factors described below,
and therefore the risk factor is rated at five:
|
UWA
|
287
• There is no possibility for obtaining spare parts as the original
manufacturer does not exist;
• No local manufacturer to provide assistance;
• High costs of re-manufacturing the main parts by others;
• Long delivery times for individually manufactured parts;
• Low success on undertaken refurbishment and modification works;
• High cost of the rework undertaken up-to date.
16.2.10. Safety of Employees
The units in question are dependent on the integrity of their hydraulic
system for proper operation under normal or fault conditions.
The failure of any part due to loss of pressure in one of the phases
could cause an unsynchronised operation of breaker phases, which in turn
could cause an internal fault and possible damage to the unit.
As these circuit breakers include high-pressure gas and oil components,
there may be a failure of its pressure vessels. An explosive outcome,
however remote, could not be ruled out, and these units present a risk to the
personnel performing maintenance work on the adjacent equipment.
They are considered a moderate risk for safety of employees, and the risk
factor is therefore rated at three.
16.2.11. Safety of Public
The equipment does not present a direct risk to the public, as their location
is well within the boundaries of the relevant substations.
|
UWA
|
288
However, there is an indirect risk through their impact on power supply that
could endanger public safety if the power supply is lost to a large area due
to an internal fault, should the unit attempt to operate under fault conditions
with low hydraulic pressure and fail.
Therefore, the risk factor is rated at four.
16.2.12. Safety of Adjacent Equipment
There is a risk associated if these units have to operate under a fault
condition with low hydraulic pressure causing an internal failure and a
rupture. The flying debris could then damage adjacent equipment, which
can be further exacerbated if, as a consequence of the failure, released oil
and gas contaminate the surrounding area and the atmosphere.
The risk factor is therefore rated at three.
16.2.13. Obsolete Design Standards
The units are considered to be an obsolete and outdated design using a high
internal pressure hydraulic system, and the high operating pressure has
caused hydraulic oil and gas losses and accelerated wearing of pumps,
valves and hoses.
The risk factor is therefore rated at four.
16.2.14. Impact on Quality of Supply
The persistent hydraulic medium leaks and subsequent failures of the
circuit breakers to operate also cause significant concern operationally.
As their failures require significant resources for often-extensive
repairs, and obtaining various parts is only possible throughoutsourcing of
|
UWA
|
289
their manufacture to local companies, they are causing inevitable delays in
returning these units back to service thus jeopardising system security as
they are installed in the following critical circuits:
WT821 Tl EP831 EP-CBK-81
WT823 A to B Busbar EP833 A to B Busbar
WT825 WT-SF-81 EP835 EP-NT-81
WT841 T2 EP841 T3
WT843 A to B Busbar EP843 A to B Busbar
WT845 WT-EP-81 EP845 EP-WT-81
MER805 T2-805 MER807 Tl-807
BU810 BU-MU-81
The WT circuit breakers are critical for the supply to major hospitals.
The circuit breakers at EP are critical for the supply of C BK
substation feeding the Westrail electrical train system.
The two M ER circuit breakers are critical, as there is only a limited
capability to supply the Merredin area from the 66kV system.
The unit at BU is critical for ensuring a secure supply to the South
west area customers and mines.
Any loss of the above circuits with the installed circuit breakers in question
would be serious and could have a long-term consequence on the quality of
supply as described above.
Their failure means an immediate loss of supply with a possible high
impact and a slow power supply restoration as it could take up to a week to
repair or replace the failed unit.
Therefore, the risk factor is rated at four.
|
UWA
|
290
16.2.15. Impact on Customer
A loss of supply to sensitive load areas as described above (hospitals, rail
system) from a failure of these units is disruptive and possibly dangerous,
as any unit could be out of service for repairs for a significant time period.
There is also an increased risk of wider protracted supply losses, if another
one of these units failed in some or the other affected circuit or substation.
Therefore, the risk factor is rated at four.
16.2.16. Impact on the Company
Any loss of supply resulting from the failure of these units in their circuits
could have a significant effect on the company's business as listed below:
• Loss of supply over a wider area means a significant loss of revenue;
• Replacement and repair of equipment under emergency regime could be
costly, especially if other adjacent plant has been damaged;
• Use of maintenance group resources to attend urgent and large repairs of
the failed unit means other planned preventive or corrective works need
to be postponed or cancelled for that year. This has an impact on the
annual maintenance plan, which could in turn jeopardise integrity and
security of operation of other equipment for which scheduled
maintenance work had to be abandoned;
• Company's relationship with customers could suffer, which is important
in the open access and increased competition environments;
• Community repercussions might be severe, particularly as some of the
circuits in question supply hospitals and rail systems;
|
UWA
|
293
16.4. Risk Ranking for the Business Case
The risk matrix assessment concludes that the total risk factor is 254 and
the number of identified special constraints is 4.
Using the table for their range as defined in Section 9.4, the risk ranking of
'High Risk' is derived from the evaluated business case analysis of the
selected and reviewed assets.
The 'High Risk' ranking means that a plan of action is required, and the
desired outcome for that action with its timeframe now needs to be selected
using the guidelines in Section 9.5, which is given in Section 16.5.
16.5. Summary of the Business Case Outcome
The outcome of this business case analysis was that the assets in question
required some work and was added to the list of Asset Future Projects from
the Asset Management Plan.
An additional analysis of the individual reviewed components has been
performed according to the guidelines in Section 9.5, which demonstrated
that the repair, refurbishment and modification options were not feasible for
these units, and that the replacement of all reviewed items would be the
only viable alternative.
Therefore, the recommendation of this business case outcome was to
prepare a submission for a capital project approval to replace the remaining
fifteen units over the next few years.
|
UWA
|
294
16.6. Discussion
The above presented business case is an example of an application of the
developed business case analysis and review of its components on a
particular non-performing asset in the transmission network.
It attempts to bring some objectivity and consistency in the way equipment
performance and its short- and long-term failure operational and financial
consequences are assessed.
By this, it is now possible to clearly and properly assess the impacts and
viability of various outcomes for the equipment identified with a poor
performance in order to determine the best way to deal with current and
future problems and their repercussions.
In the above case, a portfolio of all equipment identified as being under a
risk has been established, proper equipment age and condition analysis
done, their operational service performance and impacts on a range of areas
evaluated, and risk assessment of the relevant components completed.
An appropriate selection process has been followed, which reviewed the
required actions and their practicality and costs, and cross-referenced the
assets in question with future network development plans to exclude the
units already planned for replacement in other projects.
The benefits of the work organised through a planned long-term
replacement programme have been determined, and a proper and
reasonable best outcome for the network and the company recommended.
|
UWA
|
295
In this instance, fifteen circuit breakers were recommended for the
replacement over for the next four years (six at W T, six at EP, two at M ER
and one at BU), to be replaced as per the indicated proposed circuit breaker
replacement schedule:
Location Position Circuit Identifier Years
Western Terminal - 821, 823, 825, 841, 843 and 845 1998/1999
East Perth - 831, 833, 835, 841, 843 and 845 1999/2000
Merredin - 805 and 807 2000/2001
Bunbury -810 2001/2002
Project management, engineering design and maintenance service groups
were involved during the evaluation procedure, and were requested to
obtain and provide the necessary detailed engineering design on the
replacement plant and the relevant costing estimates, as well as to confirm
that the recommended replacement time frames were feasible.
Asset management subsequently prepared a capital project approval
proposal to the management for the circuit breaker replacement. It also
confirmed the requirements for the company's planned capital budgets for
1998/1999, 1999/2000, 2000/2001 and 2001/2002, seeking the asset owner
functions to approve and ensure the budgets contain the necessary funds to
complete this work if and when the final approval is granted.
The replacement project and the required capital funds were approved, and
the project was completed as recommended.
|
UWA
|
296
17. OVERALL CONCLUSIONS
This thesis has developed in detail the successive stages leading to the
establishment and implementation of an integrated and dynamic asset
management model for a proper and complete management of assets
installed and in service in high-voltage electricity transmission networks.
The model has been implemented, and is currently in operation in a
transmission network business. It is being fully utilised to ensure that the
described improvements are achieved, and that the benefits referred to are
brought to fruition for the business.
Most aspects of the research have now been reported in a series of
papers published in open literature and presented through lectures and
presentations, conferences, workshops, schools and business forums
covering the related subject.
The developed and presented model has been discussed and is well
accepted, after several successful internal and external audit reviews.
The research originated from an existing inability to achieve a substantial
advance in the field of asset management of the transmission network assets
in service, as they grow older.
The assets have begun to require more attention and decision making
on their current and future operation, maintenance and renewal activities.
It is also about the impact of those decisions on the performance and
reliability of the transmission network and the whole system, companies'
financial performance, and ensuring the long-term viability of the business.
It has been felt that the methodologies and systems currently
available and employed throughout the relevant industry are general in their
approach to asset management, and do not take a particular view and
|
UWA
|
297
account for the specific circumstance of the transmission business and its
environment.
The original development of the new asset management model has been in
terms of an effort to rectify this situation by achieving such a complete
model covering all aspects of the transmission asset management required
to accomplish all necessary asset management tasks.
The steps of the development from the initial situation to a new
model of asset management have been presented in the thesis throughout
Chapters 1 to 15. They contain defined work and business functions, their
roles and links, required information transfer on a defined time basis, and
supporting documentation.
The thesis starts with a detailed snapshot and analysis of the current
situation, and the summary of its findings, providing a guideline for a new
model, and resulting in recommendations to be incorporated in the new
model.
Central to those recommendations for the new model is a detailed
identification of the mechanism of transmission asset management process
and all the main work and business functions in that process, with the
improvements and additions to their current status.
The recommendations further identify improvements of their current
links and outline relationship types for a proper operation of that process.
Following this initial work in identification of the current situation and
improvements and additions necessary for a complete process, a general
structure of a new and original integrated and dynamic model and its
process is developed.
|
UWA
|
298
That includes a definition of the main policy documents covering the
companies' high-level strategy intent and its application through a policy
statement on the management of transmission assets.
Those documents provide a basis for understanding the role and
responsibility for the asset management function in the company, as well as
the expectations and goals to be achieved through its existence and
operation.
Extensive work has been done to translate the main policy documents into a
workable framework through a detailed development of an asset
management process with the definition and roles of all aspects of the
developed new model as presented in Section 6.4.
The thesis has further formulated a complete framework for the successful
implementation of the developed process by presenting comprehensive
information on business functions, necessary instructions and procedures,
and supporting documentation.
In particular, that framework consists of the initial documentation
required to start the process, procedures to be followed throughout the
whole process and the procedure upkeepers, the necessary databases and
data acquisition, the reporting from the databases to support the defined
regular exchange of information amongst the business functions, and the
necessary reviews of the exchanged information.
There is also necessary documentation for the required model supporting
roles for the defined documentation being outcomes from the required
reviews, with clear rules and instructions about required actions and
accountabilities for the recommended outcomes based on the review of
output results.
|
UWA
|
299
Extensive work has also been done to formulate the identified asset
management tasks and set of defined links, activities, and feedback in time
and content, amongst the defined business functions.
That has been completed in a dynamic and integrated way to ensure a
complete and timely exchange of prescribed information, to achieve a
significant improvement in the area of managing transmission assets.
This has been the original and envisaged aim of this research work.
Finally, the thesis has sought to explain, formulate and document the
developed model and process, and all of its procedures and documentation,
in sufficient details necessary to enable the full implementation and
operation of the developed dynamic and integrated model.
The work presented in this thesis on the development of an integrated
model for transmission asset management has gone a long way to improve
the existing situation with asset management specifically in the electricity
transmission business.
However, the presented methods, solutions and outcomes of the
model are sufficiently wide and generally applicable in their scope and
approach that they can be useful to other organisations that operate assets
and want to adopt an approach for the total management of their assets.
Despite the improvements this thesis presents, there are still many
opportunities for further in-depth research and improvements in this area
and the related subject of asset management.
They include the better optimisation of decision making on asset
actions in the business case analysis and maintenance work priority, and
automation of interlinking amongst business functions and their databases
through the increased use of computer facilities for interface links.
|
UWA
|
305
19. ACKNOWLEDGMENTS
I would like to thank a number of people who have helped, supported, and
guided me throughout my work towards the thesis as presented today:
Professor Tarn T Nguyen, my supervisor, for his absolute belief in me, and
for his strong and continuous support throughout this PhD research project;
Roy Hayes, William Wallace and Brett Hinkley for their assistance and
encouragement in the early stages of this work;
My wife, Patricia; for her love, patience, support, and understanding during
every stage of my life and my work.
I wish to sincerely thank Western Power Corporation and Doug Aberle,
General Manager Networks, for enabling me to work in the relevant areas
and on this research for mutual benefits. I also want to thank the many staff
for their support and assistance all along the way; especially to Darryl
Tweeddale, Don Hogg, Peter Chomiak, and Steve Tokic.
I also wish to thank support staff at the University of Western Australia for
their assistance whenever needed for my work.
Finally, I want to express my deep gratitude to my lecturer at the University
of Zagreb, and later manager and mentor during my first years at work,
Professor Tomislav Kelemen. He provided me with continuous and
unconditional support, assistance and encouragement towards continuous
improvements in myself and in my work.
|
UWA
|
306
20. BIOGRAPHY
Nenad Kolibas (1955) graduated in Croatia from the University ofZagreb,
Faculty of Electrical Engineering, with Honours in Electrical Engineering
in 1978. He completed postgraduate study courses in the area of electrical
engineering in 1987 at the same University.
He started his work as a cadet with KONCAR Industries Company in
December 1977 in the transformer development department, responsible for
the development of design, manufacture and testing of transformers.
He joined Western Power Corporation (then SECWA) in May 1988, and
worked in the Plant Section. He joined the Transmission Maintenance
Branch in 1994, which in 1998 folded into the Transmission Assets Branch,
and then in 2001 into the Asset Strategy Branch. He has had an active role
in a number of activities for the development, implementation and running
of the asset maintenance and management functions for transmission
network assets of the Western Power Corporation
He is a current Chairman of the Australian Standards Committee EL/13
(Measuring and Protection Transformers) and an Australian delegate in the
International Electro-technical Commission Technical Committee TC38.
He is a member of several CIGRE groups, Australian Sub-Panel
12.01, International Working Group 12.16 and a special Working Group
set- up to review asset management in transmission utilities.
He has published a number of articles and papers in national and
international journals and for conferences, and has given number of
presentations at industry forums and technical sessions.
|
UWA
|
309
22. APPENDICES
22.1. More Prominent Published and Presented Papers
3 * TRANSMISSION ASSET MANAGEMENT
1.0 INTRODUCTION
Transmission system (lines and substations) consists of many different
assets, some of them very expensive, but all with a definitive life
expectancy. As their condition deteriorates with age and operation, it is
reasonable to expect their failure in service at a certain point i ntime. When
they actually fail, the impact of such a failure could be quite serious,
ranging from a major loss of supply and prolonged restoration period,
endangering of public and employees safety, serious environmental aspects,
to significant unplanned operating and capital budget blow-outs.
Assessment of the asset condition is not a simple task, and requires a lot of
information to be collected in an organised way, often over a considerable
period of time. The actual decision to replace an old or suspect asset is
made even more difficult by a number of additional factors that have to be
taken into account, eg. planning criteria, operational circumstances, load
and fault level growth, liability risks, increased maintenance repercussions,
etc.
This paper discusses the experience of Western Power Corporation with the
development and implementation of asset management activities, some
results obtained so far through the relevant programmes, and recommends
actions to be followed in the future.
|
UWA
|
310
2.0 ASSET M A N A G E M E NT M O D EL
The asset management model adopted by Western Power defines asset
management as a set of grouped activities that cover maintenance, repair,
condition and criticality assessment, and refurbishment and timely
replacement of the assets. These activities are supported by a number of
databases, that will be addressed in more detail elsewhere in the paper.
2.1 Maintenance
Maintenance is an organised process to make sure all installed equipment is
properly inspected, checked, tested and adjusted as per agreed maintenance
provisions, and is generally divided in two main areas, maintenance policy
and maintenance work specifications.
The maintenance policy defines different levels of maintenance including
plant inspection prior to warranty expiration, the frequency and sequence or
condition trigger, and general work instructions for each level with broad
pass/fail criteria for required tests. Their contents are a combination of
manufacturers' given recommendations, utility's internal experience,
industry accepted practice and special updates on equipment performance
obtained through contacts and involvement with national and international
bodies (eg. CIGRE, IEC, etc.). The procedure for their review and update is
described further in this paper. The formal document is calledTransmission
Maintenance Policy Manual.
The maintenance work specifications are detailed, hands-on, step-by-step
servicing instructions. They originate from manufacturers' detailed
maintenance manuals, and are supplemented by own extensive experience
in maintaining the equipment. They are usually pertinent to the particular
type/model of equipment, and they prescribe skill levels for maintenance
staff, the necessary tools and plant to use, and the required standard set of
|
UWA
|
311
spare parts. The formal document is called Transmission Maintenance
Services Manual.
2.2 Repairs
An important aspect of asset management is handling of irregularities,
defects, failures and the correction of these problems, which, when done in
a competent and organised way, can greatly contribute to provision of a
safer and more reliable power supply.
A number of procedures have been developed and implemented which
define these activities, indicating their importance. The key procedures are:
guidelines for substation and line maintenance, attention to emergency
breakdowns, procedure for handling of faults and initiation of work
requests and procedure for obtaining replacement for failed plant. An
attempt is made in the following text to briefly capture the essence of these
procedures.
Irregularities and Defects
All irregularities and defects found during inspections/patrols and other
maintenance work are recorded on standard report sheets, and entered into
maintenance database against the relevant plant. Minor problems are
corrected immediately by the maintenance groups, and defects with high
expected repair costs (long outage times, new plant, extensive resources)
are referred to maintenance engineers for further assessment, approval and
repair arrangements.
The defects found on plant still under manufacturers' warranty are reported
to the project engineer who handled the relevant project/ purchase contract.
They liaise with the service or plant provider to ensure plant repair is
effected under the project or contract warranty provisions.
All defects assessed to pose imminent threat to personnel/public or
continuity of supply are referred directly to the system operations
|
UWA
|
312
controllers to arrange emergency access for their temporary or permanent
resolution.
Emergency Breakdowns
In the event of emergency breakdown the first priority of the operating
group is to make the situation (site and plant) safe and to restore the supply.
The attendance to the plant repair or replacement is then transferred to the
maintenance group.
If during any of the above incidents environmental damage or pollution
occurs, or there is the potential to cause one, maintenance engineers are
immediately contacted to arrange immediate clean-up, and to assess
environmental impacts and further remediation needs.
The maintenance engineers are required to refer any defect or problem
perceived to be a possible generic fault to the asset maintenance group for
further investigation, ie. analysis of reason for the failure and extrapolation
to predict future events.
2.3 Condition and Criticality Assessment
A higher level of asset management, often called asset management itself,
involves a number of departments and associated processes aiming to
assess plant condition and estimate its remaining safe operational life, and
to rank/prioritise plant based on the importance it presents to the operation
and planning of the system.
The processes, their dependencies and frequencies, and departmental links
and responsibilities are defined, and presented in the Manual of Asset
Procedures. All information generated from these processes is collated and
issued in a document called Transmission Asset Management Plan.
The plan will be updated annually, or more often if required by a significant
change in any of the relevant areas.
|
UWA
|
313
The main contributors to this process and their duties are described below
in more detail.
Asset Management Group
Monitors performance and ageing of plant, analyses faults and population
statistics, initiates programmes to check and assess condition of plant based
on type generic faults and the results of the plant statistics, and to determine
the plant remaining service life. It is also to analyse feedback from the plant
regular preventive maintenance programmes (eg. incurred cost movements,
spare parts consumption, amount of additional work performed, comments
on check sheets, etc.), and to modify the maintenance policies as necessary.
The group maintains close contacts with similar groups in other utilities,
and is encouraged to participate in relevant industry organisations, activities
and forums. This group is also given overall coordination for all asset
management related activities other groups perform to support this process.
Finance Group
Assists with financial matters in determination of assets fate to ensure the
financial viability of a business. The long-term business plans need to
reflect the necessary capital expenditure to replace assets as their life cycle
is expended.
Planning Group
Assesses plant criticality and the impact of its non availability on other
plant in light of transmission development plans, ie. addition of new lines
and substations and their significant alterations (eg. addition of new
circuits, fault uprates, thermal uprates, etc.). Outage times required for this
project work is also of importance, as during the worknonavailability of the
plant has a significant impact on other plant.
Operating Group
Assesses importance of lines and circuits with related plant from an
operational point of view, having knowledge of long-term outage
|
UWA
|
314
requirements requested by various internal and external users (expected to
increase with open access to the transmission grid). Impacts of seasonal
load and climate influences and generation inputs from other private
sources through the grid are also reviewed.
Projects Group
The plant specialists for lines and substations are to provide expert advice
in technical matters required at various stages of plant condition
assessment. They provide an important link to plant manufacturers for then-
valuable input where needed.
Details of all current activities (eg. investigations needed, in progress,
solution devised, being implemented, fully implemented, completed) are
kept in a Part 1- Asset Investigations of a document called Asset
Management Portfolio. An important component of all these activities is
economical analysis to decide the final outcome, which can fall in two main
groups:
la) No additional work required on plant, but units will be
removed to less important or demanding locations,
lb) No additional work required on plant, but there is a need to
increase maintenance frequency and number of spare parts. An adjustment
is made in the maintenance policy and maintenance work specifications to
reflect this decision (see 2.1 above).
2a) Plant to remain in service, but subject to refurbishment on site or in
workshop.
2b) Plant to be replaced over a period of time; possible use as a
source of spare parts to enable a partial implementation of lb).
The activities from second group are described below in more detail.
|
UWA
|
315
2.4 Refurbishments and Replacements
After completion of activities indicated above in the Part 1- Asset
Investigations, the final outcome of the processes may be a definitive need
to do something about the plant. The decision, which involved economic
evaluation, may be continuation of further service after some type of
rejuvenating action had been performed, or planned, staged removal from
service over a period of time.
Details of all current activities (ie. ongoing refurbishments, uprates,
modifications and replacement) are kept in a Part 2- Asset Current Projects
of the Asset Management Portfolio.
Details of the recommended and approved future activities (ie. schedule for
the activities listed above) are kept in a Part 3- Asset Planned Projects of
the AssetManagementPortfolio.
The long term (10-20 year horizon) asset replacement predictions will be
identified and listed in a Part 4-Future Asset Projects of the Asset
Management Portfolio.
We should bear in mind that even the final approvals are sometimes only
tentative, as in the time between regular updates decisions made by all these
groups can significantly alter basis on which the above recommendations
have been made. It is also very important for all relevant groups to always
assess the impact of their decisions on the Transmission Asset Management
Plan, and to initiate the Plan review earlier than scheduled if warranted by
these changes.
3.0 ASSET MANAGEMENT DATABASES
For all management activities to succeed it is paramount to have in place
adequate databases for data recording and proper data acquisition
procedures. The acquisition procedures ensure all relevant information is
|
UWA
|
316
collected in a timely and correct manner, and then properly entered in the
databases. The databases can be divided in two main categories:plant data
registers ( Transmission Plant ManagementSystem- TPMS, Transmission
Lines System - TLS and Transmission Ratings Information System- TRIS),
and plant activities register ( Facilities Maintenance Management System).
The purpose and main features of these databases are briefly described
below:
T P MS holds the following switchgear information - Specification and
Order Details, Technical Details, Type and Unit Details, Maintenance
Level Requirements, Current and Historical Locations, Defect Reports and
Test Results.
TLS holds the following lines information - Specification, Order and
Construction Details, Length and Number of Structures, Structure Details,
Electrical Assembly Details (conductors and insulators), Maintenance
Level Requirements and Test Results.
TRIS holds the following rating information about switchgear, substations,
and lines-Thermal and Fault Currents, Overloading and Time
Characteristics, Details of the Ancillary Components used to join Plant and
Conductors (lines and cables) and Climatic Loading Curves.
F M MS holds the following information about substations, switchgear and
lines maintenance - Location Details, Standard Type Nomination, Standard
Maintenance Levels, Maintenance Activity Type, Frequency (trigger dates)
and Cost (standard fees), Maintenance History, Outstanding Work Records,
Cost of Maintenance Work and Work Schedules.
A set of procedures has been developed and implemented to ensure
communication and reporting channels for data acquisition and recording
between all relevant groups. They include: operational areas, construction
and maintenance services, secondary systems service groups (protection,
|
UWA
|
317
communication, controls), test personnel, repair workshops, stores, regional
staff and field inspectors.
4.0 RESULTS OF SOME PROGRAMMES
The results of two programmes are presented: one studied the performance
of instrument transformers, and the other the performance of gap-type surge
arresters. The rated voltage of all equipment is 66kV and above.
a) Instrument Transformers
Consider Fig. 1 showing fault performance of the instrument transformers
for three consecutive periods (1985-1988, 1989-1992 and 1993-1996).
After a high number of major failures in 1985-1988 period, an investigation
was initiated to find the cause and remedy the situation. A few instrument
types only were found to contribute to the high failure rate. After they had
been identified, a programme was developed and implemented to test all
units from these types on site. As the number of units in service washigh,
and gaining access is not always easy, this has taken some time to
complete. All units found in unsatisfactory condition during theprogramme
have been replaced, although sometimes it was difficult and time
consuming to procure spare compatible units.
The rate of failure continued to deteriorate for the time the programmes
have begun to show effects (see result for 1989-92 period). In the end, a
total of over 70 units have been removed from service, and a significant
drop in number of major failure has been achieved for the current period
(1993-96). At the same time, population/age statistics have identified a
large proportion (56%) of our instrument transformers with age over 20
years (Fig. 2), and a programme has been created to assess their condition
|
UWA
|
318
over the next three years. The aim is to assess their remaining service life
and to prepare a long-term plan for their replacement.
b) Gap-Type Surge Arresters
Consider Fig. 3, showing fault performance of the gap-type surge arresters
for three consecutive periods (1985-1988, 1989-1992 and 1993-1996).
After a high number of major failures in the 1985-88 period, an
investigation was initiated to find the cause and remedy the situation. Only
two arrester types were found to contribute to the high failure rate. A test
programme was developed and implemented to check all remaining units in
service, which found a number of suspicious units. After consultation with
the relevant manufacturers, all affected units have been progressively
replaced, and a period of relative calm followed.
An increase in the number of failures in 1993 prompted further
investigation, and resulted in findings that some units were the problem.
But it also clearly identified the condition of aged gap-type units as a real
problem that can be expected only to aggravate as time passes. The
identified units have all been replaced, and detailed population/age statistics
have been prepared. They indicate that a large proportion (72%) of our gap-
type surge arresters are now over 20 years old (Fig. 4). A programme has
been created to test their condition over the next three years. The aim is to
assess their remaining service life and to prepare a long-term plan for their
replacement.
5.0 CONCLUSIONS
In this paper we have outlined our experience in developing and
implementing a comprehensive asset management model. Some elements
of the model have been fully implemented, others are in the planning or
|
UWA
|
320
4* MAINTENANCE STRATEGY & WHAT TO CONSIDER IN
ACHIEVING THE BEST PRACTICE IN WESTERN POWER
INTRODUCTION
Western Power Corporation (WPC) is the principal electricity supplier to
residential, commercial and industrial customers in Western Australia,
serving more than 730,000 users across an area bigger than N ew South
Wales, Victoria, South Australia and Tasmania combined. W PC is the
trading name of the Electricity Corporation established under the Electricity
Act 1994. The legislation that created the new electricity business is
intended to reduce energy prices and encourage the development of
competitive energy markets through a greater commercial emphasis in the
operation of the utilities. W PC has responded to the challenge of the
deregulated energy market by committing to an objective of achieving a
2 5% real reduction in average electricity prices by the year 2000.
The backbone of WPC's network, its transmission system, comprises 115
terminals and zone substations interconnected via 200 high voltage
transmission lines with a total length over 6,500 km. The transmission
system operates at rated voltages from 66 kV to 330 kV, with the peak
(summer) load of 2,100 M W.
The main part of the above legislative change is the decision to open access
to the transmission system for all users from 1 January 1997, enabling true
conditions for the free electricity market. This decision will re-inforce the
responsibilities of the Transmission Division, as it must embrace the spirit
of micro-economic reforms and will be required to operate the transmission
system as efficiently as possible. The manner in which it conducts its
business will come under internal and external scrutiny, and will be judged
by comparisons with industry benchmarks established on a national and an
|
UWA
|
321
international base. The transmission system maintenance costs represent a
significant portion of Transmission Division's overall expenditure, and the
proper planning and execution of its maintenance activities have a profound
effect on reliability and security of the system as a whole.
This paper presents a brief outline of the maintenance strategy adopted for
the transmission system and relevant activities and processes that have been
initiated and implemented in order to achieve goals set in that strategy.
BACKGROUND
For a very long time, going back to the 1940's, theWPCs predecessors, the
State Electricity Commission (SEC) and the State Energy Commission of
Western Australia (SECWA), were primarily involved with project and
construction activities in a desperate bid to satisfy ever growing electricity
needs of the rapidly expanding WA economy.
The main characteristic of that period was attention to repairs and
replacements after faults and failures, as the majority of the installed
equipment was reasonably new.
With passage of time, it became necessary to pay more attention to some of
the important equipment (transformers, circuit breakers), initially using
manufacturers' instructions (which were quite rudimentary in those days).
The need to seek a new approach was recognised, resulting in the creation
of line and switchgear maintenance dedicated teams. In the 1980's,
structural changes resulted different parts of the grid system being
combined (subtransmission area, old transmission area and country areas)
into a common transmission system. The maintenance responsibility was
still left divided among individual regions and a central operations group,
and they organised the maintenance work according their own
requirements, schedules and knowledge.
|
UWA
|
322
In the early 1990's, the Transmission Branch was given overall
responsibility for the maintenance of S E C WA assets within the boundaries
of its operations, described as: "The part of the S E C WA system bounded by
the HV terminals of the step up transformers at Power Stations and the
supply side LV terminals of the step down transformer circuit breakers at
zone substations, but included all step up transformers at the gas turbine
sites."
The formation of the Transmission Division and the review of the
transmission assets maintenance function in 1993 resulted in the
recommendations for the Division to assume direct control, maintenance
direction and auditing of all of its assets. That was also to include
budgeting, work scheduling and organising, and monitoring and analysing
of all the maintenance work. The review of the proposed maintenance
objectives and corporate policies, assisted by internal, external and overseas
consultants, recommended formation of a designated maintenance branch.
This Transmission Maintenance Branch would undertake all the above
activities, and ensure that the defined Corporate and Divisional objectives
and targets were met.
MAINTENANCE STRATEGY
The maintenance work has been a requirement on individuals and
organisations since physical assets have been built. Therefore, accepting
that the transmission assets exist, the Divisional policy and Branch
objectives with regard to the maintenance of the assets should be defined.
The Transmission Division Policy with regard to maintenance has been
defined as follows:
|
UWA
|
323
1. Maintain facilities in a such a condition to ensure the safety of employees,
the public and the equipment.
2. Customer satisfaction will be of a major consideration in the preparation
of the Transmission Maintenance Branch maintenance plans, i.e. reliable
supply is to be a major goal.
3. Active involvement of all employees in the development of workplace
maintenance plans and targets to ensure maximum input of corporate
maintenance rank and file knowledge.
4. Maintain facilities in such a manner that the optimum economic life of
all equipment will be achieved.
5. Strive for industry best practices.
6. Establish the true cost of maintenance for each business section, and
actively and aggressively seek to improve each of its segments.
This strategy refers to the maintenance activities associated with the
primary part of the transmission system, i.e. transmission lines and
substation. It does not cover the secondary systems, e.g. protection,
communication and supervisory control systems.
These secondary systems have similar maintenance strategies but their
consideration is outside scope of this paper. Generally maintenance work is
divided in two main categories:
1. Preventive Maintenance
This work is planned in detail and scheduled well in advance. It is
subdivided into three groups:
- Routine- This is short duration work, involving visual inspections and
minor replacements.
- Service- This is also short duration work, but involves more detailed
|
UWA
|
324
attention to equipment. A dismantling of some minor components can
occur.
- Overhaul- This is generally long duration work, requiring significant in
situ dismantling of equipment, and possible replacement of number of
components.
2. Corrective Maintenance
This type of work is generally unplanned, and requires immediate or
reasonably quick response. It is subdivided into three groups:
- Emergency- This work occurs with little or no warning and at a random
incidence, requiring urgent attention because of system or safety
implications. It is mainly in situ, but can develop to off site work.
- Deferred- Same as above as it occurs, but does not require immediate
action. It can be deferred until maintenance resources or system conditions
allow for the repair work to proceed.
- Removal- This is similar to deferred, but the equipment is removed from
site as repair work is carried out off site.
The Transmission Maintenance Branch has specified that it's strategy will
be to concentrate on the implementation of preventive maintenance in a bid
to minimise corrective maintenance, and in this way best meet the company
and division maintenance objectives. Performance measures have been
established to monitor progress in this regard.
In order to be in a position to execute the above strategy, it is important to
ensure that all equipment has preventive maintenance criteria developed
and specified, and that the necessary procedures, instructions and work
arrangements are well defined and documented. The common term and the
best description for all these areas is maintenance standards. They are
presented in more details in the following.
|
UWA
|
325
MAINTENANCE STANDARDS
A range of procedures and instructions have to be defined and documented
in order to ensure that all installed equipment is properly maintained as per
agreed maintenance provisions. They are generally known as maintenance
standards. They are divided into in three generic areas:
1. Maintenance Policy - defines different levels of maintenance for generic
equipment types (e.g. circuit breakers, batteries, lines, reactors e,tc.),
general work instructions for each level (area or parts to b teargeted) and
tests required prior/during/after work with broad pass/fail criteria for each
required test.
The levels usually include an inspection prior to expiry of warranty and two
to three maintenance levels. They start from site inspection with basic
checks, and finish with detailed site works, sometimes consisting of
disassembly and survey of all major components. Each level has its own
frequency, but they are supplemented as much as possible with condition
triggers (e.g. a number of regular or fault operations, condition of oil and
insulation, thermographic survey results, etc.). Their sequence is also
specified, as generally the higher level always encompasses the lower one's
work content.
This policy is contained in a formal document called Transmission
Maintenance Policy Manual.
2. Maintenance Work Specifications - are detailed, step-by-step servicing
work instructions for every particular brand (type and model) of equipment.
They also define skills required by maintenance staff, standard set of spare
parts, necessary plant and tools, and reporting (e.g. check sheets) for each
separate maintenance level.
|
UWA
|
326
They are formally issued as individual documents, but all linked to their
summary called Transmission Maintenance Services Manual.
3. Maintenance Procedures - are formal ways of performing maintenance.
This principally involves defining the roles of various groups involved in
the maintenance activities (and there are many of them in big organisations
such as W P C ), regulating flow of information between them, ensuring
mobilisation and repair in the event of an emergency, etc.
These instructions are contained in a document called Transmission
Maintenance Instructions Manual.
The contents of all the above Manuals and their policies are a combination
of materials that originate from a number of sources, typically:
1. The manufacturers' detailed maintenance manuals and their
recommendations.
2. Industry accepted practice and results, obtained through a long use and
exchange of information on industry forums and bodies (e.g. ESAA).
3. Internal knowledge by our own extensive experience in maintaining the
equipment.
4. Equipment performance updates made available through contacts and
involvement with national and international organisations and their
committees (e.g. CIGRE, IEC, SAA).
It is important to understand that the information contained in the above
Manuals is not, once set, fixed and valid forever. There are mechanisms put
in place which enable a constant flow of feed-back information from all the
users, and a regular review process on how to improve the maintenance
process and adapt to a constantly changing workplace and external
environment.
|
UWA
|
327
It must be emphasized that it is essential that all the above instructions and
procedures are strictly adhered to while they are current, in order to achieve
maximum benefits of the maintenance functions in the organisation.
ASSET MANAGEMENT
The asset management model that WPC's Transmission Division has
decided to use is a much wider one than is general practice. We have
defined asset management as a group of activities that cover regular
(preventive) maintenance, repairs (corrective maintenance), condition
monitoring and assessment, and refurbishment or timely replacement of
assets, i.e. their whole life-cycle process.
An important issue here is proper distinction between capital and operating
costs, as their incorrect use can greatly influence the total picture of
maintenance costs.
The lines and substations consist of various components, each with
different expected life duration. It is necessary to adjust accounting
procedures to reflect that fact, and put in place proper depreciation
procedures, which in turn will ensure correct operating vs capital outlay
budgeting.
There are many contributors to this process, and their dependencies and
responsibilities are described in a document called Manual of Asset
Procedures. All activities in the process are supported by a number of
databases that are outlined, with the main contributors, in more details
further in the paper.
All information generated from these activities is collated and form a
document called Transmission Asset Management Plan. The plan is
updated annually, or more often if there is a significant change in any of the
relevant areas.
|
UWA
|
328
THE MAIN CONTRIBUTORS
1. Asset Management Group monitors performance and ageing of
equipment, analyses faults and population statistics, and initiates repair-
replacement programmes. It also has overall co-ordination of asset
management related activities in the organisation.
2. Finance Group assists in financial matters, particularly with regard to
financial viability of the business by ensuring that the long term business
plans reflect the necessary capital and operational outlays as the life of the
equipment is expended.
3. Planning Group reviews assessed remaining life of the equipment against
the transmission development plans, i.e. to check if they are to be replaced
or upgraded as a part of system alterations due to increase in fault levels,
load levels or new customer connections.
4. Operations Group assesses importance and criticality of the relevant
equipment, and gives it a priority status.
5. Projects Group provides expert advice in technical matters, and also
estimates costs for each particular asset project.
THE ASSET DATABASES
For all asset management activities to succeed it is essential that proper
databases and acquisition procedures for collection of all relevant
information are established. The databases are divided in two categories,
equipment data registers and equipment activities registers:
1. The equipment data registers are Transmission Plant Management System
(TPMS), Transmission Lines Management System (TLMS) and
Transmission Ratings Information System (TRIS). They hold a range of
equipment technical and contract information such as type and unit details,
|
UWA
|
329
specification and order details, maintenance level requirements, current and
historical locations, defect reports, climatic loading curves, thermal and
fault ratings, overload capabilities, structure details, electrical assembly
details and test results.
2. The equipment activities registers are Facilities Maintenance
Management System (FMMS) and Transmission Protection Equipment
System (TPES). They hold equipment location details, maintenance activity
type details, frequency and cost, maintenance work history, outstanding
work and work schedules.
BENCHMARKING
Benchmarking is an important tool, which is used as part of the process to
improve the efficiency and effectiveness of the maintenance operations.
The benchmarking programme can assess the relative functional
performance (productivity vs service level) of each utility based on actual
demonstrated results and identify the practices and strategies, which have
made successful utilities "best performers".
W PC have participated in a number of consultant facilitated studies which
benchmark core functions with a number of similar utilities in Australia and
overseas countries, typically N ew Zealand, Europe and America.
Maintenance activities for transmission substations and power lines have
been benchmarked. In some areas best practice was achieved, in others
W PC was able to gain valuable information on how performance of some
core functions can be improved.
Considerable effort is made to ensure the "level playing field" throughout
the study when comparing performance. Great care is taken to minimise the
impact of currency exchange rates, variation in the application of corporate
|
UWA
|
332
5* SUMMARY FOR PRESENTATION OF MR J N KOLIBAS FROM
WESTERN POWER CORPORATION PERTH WA ON
DEVELOPMENT AND IMPLEMENTATION OF A TRANSMISSION
ASSET MANAGEMENT MODEL
WPC is the trading name of the Electricity Corporation established under
the Electricity Act 1994. The legislation that created the new electricity
business is intended to reduce energy prices and encourage the
development of competitive energy markets through a greater commercial
emphasis in the operation of the utilities.
W PC has responded to the challenge of the deregulated energy market by
committing to an objective of achieving a 2 5% real reduction in average
electricity prices by the year 2000. The backbone ofWPC's network, its
transmission system, comprises 115 terminals and zone substations
interconnected via 200 high voltage transmission lines with a total length
over 6,500 km. The transmission system operates at rated voltages from 66
kV to 330 kV, with the peak (summer) load of 2,100MW.
The main part of the above legislative change is the decision to open access
to the transmission system for all users from 1 January 1997, enabling true
conditions for the free electricity market and requiring the transmission
system to operate as efficiently as possible.
The transmission system maintenance costs represent a significant portion
of overall expenditure, and the proper planning and execution of
maintenance activities have a profound effect on reliability and security of
the system as a whole.
This presentation will give a brief outline of the maintenance strategy
adopted for the transmission system and relevant activities and processes
that have been initiated and implemented in order to achieve goals set in
that strategy.
|
UWA
|
333
MAINTENANCE STRATEGY
1. Maintain facilities in such a condition to ensure the safety of employees,
the public and the equipment;
2. Customer satisfaction will be of a major consideration in the preparation
of the maintenance plans, ie reliable supply is to be a major goal;
3. Active involvement of all employees in the development of maintenance
plans and targets to ensure maximum input of corporate maintenance rank
and file knowledge;
4. Maintain facilities in such manner that the optimum economic life of all
equipment will be achieved;
5. Strive for industry best practices;
6. Establish the true cost of maintenance for each business section, and
actively and aggressively seek to improve each of its segments.
In order to be in a position to execute the above strategy it is important to
ensure that all equipment has preventive maintenance criteria developed
and specified, and that the necessary procedures, instructions and work
arrangements are well defined and documented, and to have in place
adequate, easy to use databases and proper data acquisition procedures. The
acquisition procedures ensure that all relevant information is collected i na
timely and correct manner, and then correctly entered in the databases. A
set of procedures has been developed and implemented to ensure
communication and reporting channels for data acquisition and recording
between all relevant branches. They include operational areas, construction
and maintenance services, secondary systems service groups, test
personnel, repair workshops, stores, regional staff and field inspectors.
|
UWA
|
335
ASSET MANAGEMENT
Asset management is a group of activities that cover regular (preventive)
maintenance, repairs (corrective maintenance), condition monitoring and
assessment, and refurbishment or timely replacement of assets, ie their
whole life-cycle process.
A Asset Management Procedures Manual
Al Asset Management Responsibilities
A2 Asset Management Databases
A3 Asset Management Decision Process
B Asset Management Portfolio
Part 1 - Assets Under Review- Plant Directory - This represents a
complete list of all our primary assets showing our transmission network
consisting of primary equipment and transmission lines.
- Plant Under Review - This consists
of a review of plant in the above directory. All available information that is
relevant to the plant in question has resulted in a list of plant to be
considered for inclusion in asset management plan and for further
investigation. The items chosen to be reviewed first have been initially
assessed as the ones representing items of maximum age, items with a large
number of units removed from service, items with the highest number of
faults or overall maintenance incidents or costs.
- Sundries - It contains minutes of
meetings of various groups involved in this work, the relevant
correspondence, and other working items.
|
UWA
|
336
Part 2 - Asset Future Projects -0-5 years - Plant to be considered for
action within the next five years, with the recommended type of action and
timing.
-6-10 years - Plant to be considered for action in 6-10 years, with the
recommended type of action and timing.
- over 10 years - Plant to be considered for action after 10 years, with the
recommended type of action and timing.
Part 3 - Asset Investigations - Before or during assessment of certain
items of plant under review it is necessary to obtain additional information
about the plant. This also includes number of tests and measurements, and
various trials and joint research projects with other authorities, companies,
universities and manufacturers.
An important component of all these activities is an economic analysis to
decide the final outcome, which can fall in two main groups:
la) No additional work required on plant, but units are
to be reallocated to less important or demanding locations.
lb) No additional work required on plant, but it will be
necessary to vary maintenance frequency or maintenance service
instructions to reflect these requirements (eg. different servicing
frequencies, changed scope of work during service, etc.).
2a) Plant is to remain in service, but it will be subject to
refurbishment or modification on site or in a workshop.
2b) Plant is to be replaced over a period of time;
possible use as a source of spare parts to help with activities in lb).
Part 4 - Update of Manuals - Policy Manual or Services Manual
- As a result of plant investigations and reviews it is possible that some
outcomes would not point to the need to perform a refurbishment,
modification or replacement of the plant. The identified problems could
|
UWA
|
338
6* ROLE OF ASSET M A N A G E M E NT IN THE
DEREGULATED ELECTRICITY INDUSTRY
I INTRODUCTION
A power utility system (lines, substations, feeders) consists of many
different assets, some of them very expensive (eg major terminal
transformer units are worth around $4.5 M). For example, Western Power
Corporation (WPC) Transmission System consists of 115 terminals and
zone substations, comprising approximately 13,000 individual items of
plant, interconnected with high voltage transmission lines in excess of 200
in number and with a total length of 6,500 km. The transmission system
operates at rated voltages from 66 to 330 kV, with the peak (summer) load
of 2,350 M W. All the above items have a finite life expectancy. Their
condition normally deteriorates with age, use and operation, and it is
reasonable to expect they will fail in service a at certain point in time.
There are number of issues associated with the actual failur eincidents).
The impacts of such failure could be quite serious, ranging from major loss
of supply and prolonged restoration period, loss of revenue, customer
losses, endangering of public and employees safety, serious environmental
aspects and possible litigation consequences, to significant unplanned
operating and capital expenditures.
Additionally, the now deregulated energy market and the spirit of micro-
economic reform place increased pressure on W PC to operate the electricity
system as efficiently and economically as possible. The manner in which it
conducts its business in the open access environment will come under
industry and government scrutiny, and will be judged by comparisons with
industry benchmarks established on the performance of national and
international utilities.
|
UWA
|
339
Asset management represents a comprehensive approach to dealing with all
the above issues. This process is a dynamic one, ie it must be repeated
regularly to ensure all changes in other development plans are promptly
accounted for. The long-term view (10-20-year horizon) and dynamism of
the process are the main characteristics of properly implemented and run
asset management process.
This paper discusses the reasons for the development and experience
obtained with implementation of an in-house asset management system and
the impacts on future activities.
II. ASSET MANAGEMENT MODEL
The asset management model adopted by Western Power defines asset
management as a set of grouped activities that cover maintenance and
repair, condition and criticality assessment, refurbishment and timely
replacement of the assets.
A. Maintenance
Maintenance is an organised process to make sure all installed equipment is
properly inspected, checked, tested and adjusted as per the agreed
maintenance provisions. It is formed of three main areas, namely
maintenance policy, maintenance work specifications and maintenance
procedures.
1) Maintenance Policy: This defines different levels of maintenance
including plant inspection prior to warrant yexpiration, the frequency and
sequence or condition trigger, and general work instructions for each level
with broad pass/fail criteria for any require dtests. It is derived from a
combination of manufacturers' given recommendations, the utility's
internal experience, industry-accepted practice and special updates on
|
UWA
|
340
equipment performance obtained through contacts and involvement with
national and international bodies (eg CIGRE, IEC). This policy is specified
within the Maintenance Policy Manual.
2) Maintenance Work Specifications7 These are detailed, hands-on, step-by-
step servicing instructions. They originate from manufacturers' detailed
maintenance manuals, supplemented by extensive in-house experience in
maintaining the equipment. They are usually pertinent to the particular
type/model of equipment, and they prescribe skill levels for maintenance
staff, the necessary tools and plant to use, and the required standard set of
spare parts. The work specifications are defined within the Maintenance
Services Manual.
3) Maintenance Procedures: These are written instructions that define how
to handle a diversity of maintenance work (eg substation and line
maintenance, emergency breakdowns, handling of faults and initiation of
work requests, obtaining replacements for failed plant, etc). The procedures
are defined within the Maintenance Instructions Manual.
B. Asset Management Plan
An Asset Management Plan is the end result of the involvement of number
of branches in the asset management processes. It aims to assess plant
condition and estimate its remaining useful and safe operational life in
order to define any actions required on plant, based on the importance it
presents to the operation and planned enhancement of the system.
The outcome of these activities can fall in two main groups:
a) No additional work is required on plant, and it will be removed to a
less important or demanding location, or its maintenance frequency or
scope of work will be changed.
b) Plant requires some action, where plant will remain in service, but
undergo work on site or in the workshop, or it is to be replaced over a
|
UWA
|
341
period of time. Some units may be used as a source of spare parts to back
up units in service during implementation of the replacement project.
The Plan is updated annually, or more often if there are significant changes
in any of the relevant areas.
The above processes, with links, dependencies and responsibilities of the
branches involved are defined in the Manual of Asset Management
Procedures. A brief description of the branches involved is given below.
I) Maintenance Branch: This group monitors performance and ageing of
plant, analyses faults and population statistics, initiates programmes to
check and assess condition of plant based on generic type faults and the
results of the plant statistics, with the objective to determine plant
remaining service life. This group is also responsible to analyse feedback
from regular preventive maintenance programmes (eg incurred cost trends,
usage of rotational spares, amount of additional work performed, comments
on check sheets). The group maintains close contacts with similar groups in
other utilities, and is encouraged to participate in relevant industry
organisations, activities and forums.
This group is also given overall coordination for all asset management
related activities other groups perform to support this process.
2) Finance Branch: It assists with financial matters in determination of the
assets fate to ensure the financial viability of a business. The long-term
business plans need to reflect capital and operating expenditures to repair or
replace assets as their life cycle is expended.
3) Planning Branch: It co-ordinates transmission development plans and
obtains capital project approvals.
4) System Operations Branch: It determines the importance of critical lines
and circuits from an operational point of view that enables proper planning
of plant work based on system reliability and open access obligations.
|
UWA
|
342
They also assess system long-term outage requirements, based on requests
by internal and external users (expected to increase under open access
regime), to determine optimum timing for plant replacement.
5) Projects Branch: It provides specialist technical advice and project cost
estimates required at various stages of plant condition assessment. They are
the link to plant manufacturers for their input where needed. They also run
the replacement/refurbishment projects after approval is granted.
III. REFURBISHMENTS AND REPLACEMENTS
After completion of activities indicated above there may be a specific need
to do something about the plant. The decision, which involves operational,
safety, environmental and economic evaluation of the plant, may be to
continue its further service after some type of rejuvenating action has been
performed, or to plan staged removal of plant from service over a period of
time. Details of proposed activities and their background must be presented
in an open way, so that the work and consequences are transparent to all
users of the system under open access rules.
- Current activities are listed as Asset Current Projects, (ie ongoing
refurbishment, uprate, modification and replacement works).
- Details of the approved future activities are kept as Asset Planned Projects
(ie scope of work, timing, risk assessment).
- The long-term (10-20 year horizon) requirements for asset works are
identified and listed as Future Asset Projects (ie asset condition, critical
impact analysis, end of economical life prediction, proposed action and its
timing). It should be borne in mind that even the final approvals to proceed
with the work are only tentative. As time passes and work progresses,
various decisions are made by the above groups and other users of the
system (current and potential) that can alter the basis on which the above
|
UWA
|
343
recommendations had been made, prompting changes to the asset
management plan.
It is therefore important that all relevant groups are aware of the asset
management plan details, and that they assess the impact of their decisions
on the plan. They need to initiate review of the plan earlier than any
scheduled annual update cycle if warranted by these decisions.
IV. RISK MANAGEMENT AND INSURANCE CONSEQUENCES
The above structured approach to the monitoring of plant performance,
continuous assessment of its condition, and preparation of dynamic action
plan to address any found problems, presents an excellent basis for
appropriate Risk Management of the company's business.
Risk Management is recognised as an integral part of good management
practice. It enables W PC to minimise losses and maximise opportunities for
improvements. Where risks cannot be minimised or eliminated, at least not
in the short term, they will be covered by appropriate insurance policies to
safeguard the Corporation's financial viability.
The benefits of having a comprehensive Asset Management Plan in terms
of risk management are a reduction of incidents, high standards of
accountability, reduction of insurance premiums and a reduction of the
potential risks of liabilities for WPC.
V. ASSET INFORMATION ACQUISITION
In order that all the above asset management activities and processes
succeed, it is paramount to define required datasets and to implement
adequate procedures for their acquisition. The acquisition procedures
|
UWA
|
344
ensure all defined relevant information is collected in a timely and correct
manner, and then properly entered in the databases.
A number of procedures have been developed and implemented to
ensure that communication and reporting channels for data acquisition and
recording between all relevant groups takes place. They include:
operational areas, construction/ maintenance services, systems service
groups, test personnel, repair workshops, stores, regional staff and field
inspectors.
VI. RESULTS OF SOME PROGRAMMES
A. Change of Maintenance Policy
A 66 kV bulk oil type circuit breaker maintenance procedure was found to be
very expensive and of long duration, and an investigation was initiated. It
was found that the actual work could be changed to three different levels,
instead of the only one currently used, as not all the work was needed every
time. After detailed analysis of various work and cost options, it was
recommended to change its maintenance policy by initially performing only
the lowest level of maintenance every four years or after a prescribed number
of fault operations. This includes contact resistance measurements and oil
quality tests. The test results are then used to determine if the new level two
(on-site oil filtering) or level three (on-site oil change and contacts servicing)
is required. The necessary changes were also made in its maintenance service
manual.
B. Change of Maintenance Service Level
A number of 132 kV circuit breaker units were reported with badly
corroded pull rods and coupling pieces during their regular maintenance. A
couple of units were fully dismantled and a careful examination of all parts
|
UWA
|
345
was arranged. Based on the result of inspections and information obtained
from the manufacturer it appeared that corrosion was completely random
and not related to any particular batch. The parts in question were supposed
to be designed for outdoor use without experiencing corrosion.
After reviewing all available data a decision was made that the most
economical and practical solution was to change maintenance service level.
All affected units are now subject to changed working instructions during
their servicing. They include a mandatory dismantling of rods and coupling
pieces, and inspection of their condition during every level 'B' type
maintenance work. The parts are brushed, cleaned with a solvent and
greased with a special resin based corrosion preventive compound for
outdoor use. In the event any pull rod is corroded too badly, the rods on all
three phases must be replaced as design of the pull rods has been slightly
modified compared to the old design. The manufacturer has agreed to
supply necessary number of new parts to replace all rods and coupling
pieces corroded beyond repair free of charge.
C Refurbishment Project
After several explosive failures of this a 22 kV circuit breaker type, an
investigation was initiated that revealed a generic design problem (main
gaskets insulation deterioration). This in turn lead to leaking of the internal
insulating compound and ingress of moisture, causing internal flashover
and failure. The problem of finding a solution to prevent this problem was
exacerbated by a presence of PCBs in the insulating compound dating back
to its original filling time. An innovative removal and repair procedure has
been developed and implemented, with the manufacturer's input. It was
assessed that was a better option than to replace the affected units.
It was recommended to replace all poles on the affected circuit breakers
with refurbished poles during normal maintenance work, and to send them
|
UWA
|
346
back for further refurbishment to be used on the next site. A special
working area was set up in the workshop. A few spare pole sets were found
in the store, and refurbished to enable this work to be completed on circuit
breakers in service.
D. Replacement Proposal
A number of gas insulated circuit breakers of particular type have been
identified with constantly leaking gas, causing repeated loss of gas alarms
and requiring frequent re-gas of the units on site. It posed a threat to
electricity supplies and to system security. Also, the release of a free SF6
gas in the atmosphere is not environmentally acceptable, as it has a very
high Greenhouse Warming Potential. Additional maintenance costs for SF6
gas and maintenance crews attending the faults have been assessed.
The manufacturer has abandoned this circuit breaker model, therefore spare
parts would be very difficult to obtain. This would result in long waiting
periods and very high costs to manufacture them on an individual basis.
Adjacent equipment is at risk as the units may operate under fault
conditions with insufficient gas pressure within the unit to guarantee its
100% safe operation.
Any loss of these circuits would mean complete loss of supply to sensitive
load areas, and in most instances for a protracted period, depending on the
ability of the system to temporarily feed customers from alternate sources.
There would be a significant production time lost in mine site operations,
and disruption of supply to any townships affected. Loss of associated
circuits would also have had a significant effect on the Western Power
business, as it would mean significant loss of revenue. The replacement and
repair of equipment under emergency conditions would be very costly,
particularly if other adjacent plant had been damaged. Western Power's
|
UWA
|
347
relationship with its customers would suffer, which is very important in the
open access and increased competition environment.
A serious attempt was made to resolve these problems through repair or
redesign through a number of initiatives and investigations, involving the
manufacturer and W PC staff. Five leaking units were completely
dismantled and resealed with new gaskets, but the leaks repeatedly re-
occurred on three units within a short period of time. This method was
therefore abandoned due to high costs, difficult access to units and low rate
of success. It was considered that the costs and risk of further failure were
too high to continue this programme and they needed speedy replacement.
A detailed economic evaluation of their replacement costs vs
repair/maintenance costs (life cycle cost analyses) shows favourable returns
for W P C. It was therefore recommended that the circuit breakers in
question should be replaced.
VII. CONCLUSIONS
This paper has outlined our experience in developing and implementing a
comprehensive asset management model to support our business in the
deregulated electricity market. The main purpose and characteristics of
asset management model components have been described, as well as the
processes to ensure proper update and maintenance of the Asset
Management Plan.
A few examples were presented to indicate how problematic plant is
identified, assessed, appropriate action taken based on available data, and
major problems avoided by dealing with the problem in a proper and timely
manner.
This model should enable Western Power to properly manage its assets and
achieve the prevention of problems derived from ageing, supply
|
UWA
|
349
7* ADVANCING TRANSMISSION ASSET MAINTENANCE AND
MANAGEMENT
1.0 INTRODUCTION
A transmission system is made up of a very large number of individual and
very different assets. With their condition deteriorating with age and
operational use, it is reasonable to expect their failure in service at a certain
point in time. The impacts of such a failure could be quite serious,
depending on their type, location, size and cost. A supply authority is faced
with a range of outcomes, which may be major loss of supply and
prolonged restoration period and endangered public and employees' safety.
Serious environmental aspects and liability issues, and significant
unplanned operating and capital budget costs could also occur.
Therefore it is considered important to implement a formal system to
continually assess asset condition, and present and review an action plan to
deal with those assets under review, based on their total life-cycle cost. This
is not a simple task, and requires detailed information before any decision
can be made. Such information includes asset condition and residual life,
planning criteria, operational circumstances, expected load and fault level
growth, potential liability risks, increased maintenance, etc.
This paper discusses how Western Power Corporation is dealing with the
above issues using in-house developed and implemented asset management
procedures.
2.0 ASSET MANAGEMENT MODEL
The asset management model adopted by Western Power defines asset
management as a set of grouped activities that cover maintenance and
|
UWA
|
350
repair, condition and criticality assessment, refurbishment and timely
replacement of the assets. A flow chart of the Asset Management Model is
presented in Fig. 1.
2.1 Maintenance
Maintenance is an organised process to make sure all installed equipment is
properly inspected, checked, tested and adjusted as per agreed maintenance
criteria. It is formed of three main parts that are; maintenance policy,
maintenance work specifications and maintenance work procedures.
The maintenance policy defines the different levels of maintenance criteria
and general scope of work with broad pass/fail criteria for any required
tests. The maintenance work specifications are detailed plant servicing
instructions for the particular type and model of equipment. The
maintenance work procedures define how to perform a variety of
maintenance functions.
Working groups are made up of a cross-section of maintenance, design and
asset management staff who develop and update the above documents.
2.2 Condition and Criticality Assessment
Asset management staff monitor the performance and ageing of plant by
analysing population fault and maintenance statistics. The results are then
used to initiate testing programmes to check and assess the condition of
suspect plant and to determine the remaining service life.
This data gathering and analysis also uses feedback information from
regular preventive maintenance actions (eg incurred cost trends, spare parts
consumption, additional work performed, comments on check sheets, etc)
together with information from other groups, eg Finance, Planning,
Operating and Project areas.
The whole process is presented in the flow chart shown in Fig 1, with
details of the processes and the dependencies of departmental links and
responsibilities defined in the Manual of Asset Procedures.
|
UWA
|
351
After reviewing the information obtained throughout the above processes,
the final outcome of the assessment study can fall into one of two groups:
2.2.1 No additional work is required on plant, but there is a need to adjust
information in one of the three maintenance manuals (on maintenance
policy, maintenance work specifications and maintenance work procedures)
to reflect this decision,
2.2.2 Plant will require certain actions, ie continue service after being
subjected to repair or refurbishment to remedy the cause of the problem, or
to be replaced over a period of time.
2.3 Asset Management Plan
All information generated from the asset management process is collated
and issued in a document called the Asset Management Plan. The Plan
contains details of all current activities (ie policy document updates and
ongoing refurbishments, uprates, modifications and replacements) and of
the approved future activities.
It also shows an expected long-term (10-20 years) strategy for any
actions needed (ie predicted replacement and repairs).
The Plan is updated annually, or more often if required as indicated by any
significant changes in the relevant areas. Therefore it is very important for
all relevant groups to assess the impact of their plans and decisions on the
Transmission Asset Management Plan, and to initiate its review and change
earlier than scheduled if warranted.
The Asset Management Plan also presents an excellent base for appropriate
risk management studies. Risk Management is recognised as an integral
part of the Company's business management.
|
UWA
|
353
3.0 ASSET MANAGEMENT DATABASES
All asset management activities need to be adequately recorded on suitable
databases to enable correct analysis of plant performance. Data acquisition
procedures are set to ensure that all relevant information is collected i na
timely manner, and then correctly entered into the relevant databases. The
databases are divided in two categories; plant data registers and plant
activity registers.
A number of procedures have been developed and implemented to ensure
that adequate communication, reporting and recording of data is achieved
among all relevant groups. These groups include operational areas,
construction and maintenance services, secondary systems services, test
personnel, repair workshops, stores, regional staff and field inspectors.
4.0 ASSET MANAGEMENT ASSESSMENT STUDY
There are number of issues that need to be considered before a proposal is
presented for any action required of a particular item of plant. They are
listed below with relevant comments on their priority, associated weighting
factors, risk evaluation, and cost implication (life cycle cost assessment):
4.1 Age
The age of the units is taken in account, and is given a low-weighting
factor. The risk factor is calculated from the current age against the total
expected life of plant.
4.2 Frequency of Failures
The frequency of failures is given a high-weighting factor as it
influences network performance, increases maintenance costs, causes loss
|
UWA
|
354
of supply and revenue, and reflects badly on customer satisfaction. The risk
factor is based on the number of failures per unit per year.
4.3 Condition
The condition of units can be a significant factor, which leads to failures
and uncertainty of future performance, and is given a medium-weighting
factor. The risk factor is based on the amount of additional maintenance
work required in excess of regular preventive maintenance for a particular
plant model.
4.4 Environmental/Regulatory Requirements
Normally plant is sufficiently well designed to avoid any significant impact
on the environment, so the weighting factor is rated as medium. The risk
factor is based on the effects of any possible release of gas in the
atmosphere or oil in the ground.
There is a special constraint to be considered where the risk factor of 5 is
assigned, ie an immediate action plan is required. The reason might be
associated with new obligatory legislation, or plant that is situated on
environmentally sensitive areas (eg underground water catchment), etc.
4.5 Maintenance Costs
The maintenance costs are a significant portion of the company's operating
expenditure. These costs are then compared against the costs to repair,
refurbish or replace the plant under consideration. Appropriate life cycle
cost evaluation is then undertaken to find the most economical solution.
They are given a medium-weighting factor. The risk factor is based on the
total maintenance costs over the cost for new equipment of the same
characteristics.
4.6 Replacement Costs
A proposal may be to replace the defective units with a new model that
requires very little attention. It this then weighted against the repair or
refurbishment options through an economic analysis of the remaining in
|
UWA
|
355
service life, and is given a medium-weighting factor. The risk factor
assigned is based on the ratio of new against existing costs.
4.7 Spare Parts Availability
This issue is very important, as a number of manufacturers have ceased to
exist or have abandoned making the particular model or spare components.
In the case of a major fault occurring, spare parts could be very difficult to
obtain, which would result in long waiting periods or very high costs to
manufacture the parts on an individual basis. Therefore a high-weighting
factor is assigned. The risk factor is determined from the number of main
parts currently available, their costs and delivery periods.
There is a special constraint to be considered where the risk factor of 5 is
assigned, ie an immediate action plan is required. The reasons may be that
no spare parts could be obtained from any source, or their delivery periods
and costs are considered extreme.
4.8 Competency of Employees
The skills to repair or completely refurbish the affected unit within Western
Power are assessed, and this could significantly influence any final
decision. A medium-weighting factor is assigned. The risk factor is
determined from available skills analysis.
There is a special constraint to be considered where the risk of 5 factor is
assigned, coincident with the risk factor assigned in 4.9, ie an immediate
action plan is required. The reasons may be that no skills exist to attend the
affected plant, or a location where extreme repair periods and costs would
be incurred.
4.9 Availability/Cost of Refurbishment Services
The skills to repair or completely refurbish the affected unit external to
Western Power are also assessed, and influence any final decision. This is
given a medium-weighting factor. The risk factor is determined using a
combination of factors described previously.
|
UWA
|
356
There is a special constraint to be considered where the risk factor of 5 is
assigned, ie an immediate action plan is required. The reasons may be that
no skills exist to attend the affected plant, or a location where extreme
repair periods and costs would be incurred. The decision on risks for both
areas 4.8 and 4.9 may be a combination of factors listed below:
a) Difficulty in obtaining spare parts,
b) Remote locations of the units in question,
c) Difficulty in arranging longer access to these units (eg feeders
supplying mining sites),
d) Low success rate on previously trialed refurbishments and
modifications,
e) High cost of the rework required.
4.10 Safety of Employees
The units in question may also pose a risk for the crew that performs work
on adjacent circuits, as the unit may operate under fault conditions with
insufficient security to guarantee its safe operation. Therefore this is given a
high-weighting factor. The risk assessment is based on the probability that
maloperation or failure could lead to incidents.
There is a special constraint to be considered where the risk factor of 5 is
assigned, ie an immediate action plan is required.
4.11 Safety of Public
Equipment maloperation may present a direct risk to the public. That is a
direct risk in the form of flying debris or exposed live conductors. It may
not always be possible on occasions to mobilise a crew to site in sufficient
time to quickly restore customer supply, leading to hazards occurring in the
general public domain. Therefore this is given a high-weighting factor. The
risk is assigned on the probability of an incident occurring, its possible
duration, and the size and type of location that could be affected by the
plant failure.
|
UWA
|
357
There is a special constraint to be considered where the risk factor of 5 is
assigned, ie an immediate action plan is required.
4.12 Safety of Adjacent Equipment
There is a real risk associated with suspected units having to operate under
fault conditions, as any adjacent equipment could be damaged by flying
debris, further exacerbating the consequences of failure, and could cause a
further release of any contaminated particles into the atmosphere. This is
given a medium-weighting factor. The risk is assigned on the probability of
an incident occurring, its possible duration, and the size and type of location
that could be affected by the plant failure.
There is a special constraint to be considered where the risk factor of 5 is
assigned, ie an immediate action plan is required.
4.13 Obsolete Design Standards
Sometimes units are considered to be of obsolete design, with inherent
design imperfections, poor tolerances, etc, causing failures (eg jamming of
operating mechanisms), but generally perform their duties as required. This
instance is given a low-weighting factor. The risk is assigned on the
probability of an incident occurring, its possible duration, and the size and
type of location that could be affected by the plant failure.
4.14 Impact on Quality of Supply
Any loss of supply from affected circuits has consequences on quality of
supply. It could cause complete loss of supply for a protracted period,
depending on the ability of the system to temporarily feed customers from
alternate sources. This is given a high-weighting factor. The risk is assigned
on the probability of an incident occurring, its possible duration, and the
size and type of location that could be affected by the plant failure.
There is a special constraint to be considered where the risk factor of 5 is
assigned, ie an immediate action plan is required.
|
UWA
|
358
4.15 Impact on Customer
Any loss of supply could lead to a long and very disruptive loss of supply,
sometimes to sensitive load areas. There could be significant production
time lost in mine site operations, disruption of supply to general public, etc.
This is given a high-weighting factor. The risk is assigned on the
probability of an incident occurring, its possible duration, and type and size
of customer(s) that could be affected by the plant failure.
There is a special constraint to be considered where the risk factor of 5 is
assigned, ie an immediate action plan is required.
4.16 Impact on Western Power
Any loss of supply could have a significant effect on the Western Power
business as listed below:
a) Loss of supply over a significant period of time would mean
significant loss of revenue,
b) Replacement and repair of equipment under emergency situations
would be very costly, particularly if other adjacent plant has been damaged,
c) Western Power relationship with customers would suffer, which is a
very important consideration in the environment of open access and
increased competition,
This is given a high-weighting factor. The risk is assigned on probability of
an incident occurring, its possible duration, cost to restore to the original
condition, and the amount of revenue that could be lost by the plant failure.
There is a special constraint to be considered where the risk factor of 5 is
assigned, ie an immediate action plan is required.
4.17 Ability to Manage the Replacement Process
The Company's ability to manage the replacement process by adequate
equipment condition assessment and the long term planning to replace
|
UWA
|
359
equipment that is under risk, rather than be failure driven with all the
associated consequences is important.
This is undertaken by suitable equipment condition and risk assessment
processes, the selection of an adequate course of action to deal with the
risks, implementing operational arrangements to ensure secure supply and
the safety of operational staff, and the timely ordering of replacement
equipment.
It is also prudent business sense that action is taken to limit the potential
risks, and realise any possible savings in long term operating costs by
arranging suitable plant replacement programmes.
5.0 REFURBISHMENT PROJECT
An example of the application of the process discussed above follows,
using a combination of weight and risk factor analysis.
After several explosive failures of a 22 kV circuit breaker type, an
investigation was initiated that revealed a generic design problem (main
gasket insulation deterioration). This in turn lead to leaking of the internal
insulating compound and ingress of moisture, causing internal flashover
and failure. The problem was to find a solution to prevent this problem.
A full assessment study has been undertaken using this process
where all aspects of the case were reviewed, as per the above clauses 4.1 to
4.17.
An innovative removal and repair procedure has been developed and
implemented with the manufacturer's input, enabling the company to use
local skills and parts in an economical way.
It was then recommended to change all poles on the affected circuit
breakers during normal maintenance work with poles previously
refurbished in the workshop. This solution was particularly cost effective,
|
UWA
|
360
compared to the replacement of all units with new equipment, as there were
spare poles for refurbishment in abundance from other failed units.
This has also represented a permanent fix for the duration of the
remaining life of the units in question, as they have already passed more
than a half of their expected service life.
6.0 CONCLUSIONS
In this paper we have outlined our experiences in developing an in-house
asset management model, to enable proper and cost effective long-term
management of our transmission equipment.
The purpose and characteristics of the main elements of one part of the
model have been described (asset management strategies), as well as the
need and methods employed to ensure proper information acquisition is
undertaken to support the process.
The importance of including life-cycle costs to determine the long-term
asset management plan has been emphasized. This will achieve the
continuous security and reliability of the system and the financial viability
of the business, while addressing defective plant in an orderly fashion.
Such a structured approach to the monitoring of plant performance and
planning of any remedial actions presents a sound basis for appropriate
Risk Management of the Company's business.
This model now enables Western Power to properly manage its
transmission assets in the long term by preventing problems derived from
ageing plant. This will avoid major supply interruptions, unexpected high
expenditures, risk of premature asset replacements, and will result in
substantial benefits to all users in an open access environment.
|
UWA
|
361
9* TRANSMISSION INFRASTRUCTURE REPLACEMENT M O D EL
1.0 INTRODUCTION
The previous paper "Asset Management' has briefly outlined an asset
management model and its structure, relevant procedures and supporting
documentation that are used to manage the transmission infrastructure.
In this paper we will now cover those activities in more detail to show
which asset performance reports are prepared and analysed, and how are
they used to assess and review asset performance.
These reports highlight equipment in poor condition or not performing,
which should than be further reviewed to determine the need for further
action for asset over certain period of time.
The reports also identify processes that are not satisfactory and need
review. The outcomes of these activities and relevant recommended actions
are presented in a document called the 'Asset Management Plan'.
The paper also presents more details about the 'Asset Business Case
Analysis' process, ie how to prepare an asset business case for management
approval to ensure recommended action is effected in a required time frame.
2.0 MAIN ASSET PERFORMANCE MANAGEMENT REPORTS
2.1 Plant Corrective Maintenance Report
This report is produced fortnightly to monitor and review all maintenance
work other than preventive maintenance work as defined by the criteria
document, ie outside preventive maintenance regimes.
|
UWA
|
362
The report contains the following details, which are used to analyse regular
performance of assets, to calculate number of plant failures and to produce
a number of other performance statistic data (explained later in this
document):
facility denominator (switchyard or line name, circuit and phase
details),
description of fault,
work request details (when fault reported, cost estimate, work
priority assessment),
corrective action taken,
time of repair,
cost of repair,
type of asset (manufacturer name and asset type description),
asset serial number,
work order number,
repair crew identification code,
corrective action type,
success of repair work (completed, partially done and what is the
outstanding work required, not done as other work required, cancelled).
When the report is produced, all listed corrective maintenance work is
analysed to check which activities were performed during the preventive
work, and which not. Those performed as part of preventive work are
deemed plant faults, but are not included in plant failures statistic.
Those activities performed on their own, and not during preventive
work, are then assessed to prepare them for data entry in the plant failure
data base. This process and relevant coding is described below in 2.2.
Checking of each corrective maintenance activity involves more then
|
UWA
|
363
just the details of the particular activity. It also includes review of all
maintenance work done on that plant beforehand.
They are several reasons for it:
has this type of repair occurred before, and how many times,
was it before or after preventive maintenance, and how far away,
what type of repair procedures was applied in the past (same or
different),
was the repair performed by the same or different crews.
Based on the above information it is now necessary to make decision if it is
necessary to proceed with further investigation of performance and
condition of the particular plant, and to consider benefits of repair,
refurbishment, and modification and replacement process.
2.2 Plant Failure Report
Only the maintenance activities done separately from the regular preventive
maintenance work (ie requiring special access to plant between regular
maintenance intervals) are counted as a plant failure.
Such corrective activities of plant should be reviewed and assigned a proper
failure code according to the list below:
F Faults, which cause loss of supply (forced outages)
- FV Violent, explosive, type of failure.
- FM Unit is repaired on site after failure.
- FR Unit is removed from site and discarded.
- FRRUnit is removed from site, repaired and returned to site or to store.
M Faults, which do not cause loss of, supply (and allow units in service
until an outage can be arranged)
|
UWA
|
364
- MM Repairs are completed on site.
- MR Unit is removed from site and discarded.
-MRR Unit is removed from site, repaired and returned to site or to store.
This report should be produced at least every month to perform a detailed
analysis of fault and equipment type represented in these failures.
The plant is analysed by type, ie a separate report is prepared for specific
plant (eg circuit breakers, power transformers). The results for same or
similar models/voltages are aggregated to highlight problematic items.
2.3 Asset Performance Reviews
To measure success of the asset management process there is a need to
assess how it is meeting its stated company set performance indicators for
plant performance by reviewing performance of the transmission network.
Some of the indicators that should be used in such process are listed below:
A number and assessment rating of site inspections,
A percentage of overall plant failures,
A percentage of faults during plant maintenance,
Number of explosive failures,
Number of conductor and polers on ground after faults,
Line failures per 100 km,
Number of emergency outages with and without loss of supply.
2.4 Plant Performance Statistics Review
The relevant staff from Asset Management and Asset Services Branches
will assess performance of the network assets over the previous three
months to establish plant performance trending indicators by reviewing all
available statistics (failures, maintenance, emergencies and forced outages)
during their regular quarterly review meetings.
|
UWA
|
365
The main focus of the review is to analyse the above performance reports
and to exchange relevant information for future actions or on success of
current remedial actions already in progress.
The main issues to be discussed and evaluated are:
frequency of faults and failures per plant types,
new environmental and regulatory requirements,
maintenance costs of repairs and preventive work,
re-occurance of faults,
spare parts availability,
competency of employees,
availability and costs of external repair and refurbishment services,
safety of maintenance practices.
2.5 Plant Planning Reviews
The relevant staff from Asset Management, Planning and Operations
should meet on regular basis to assess future network developments, asset
plan requirements, and mutual impact of these plans on current and future
asset projects and system operations.
They should also review performance and trend indicators of the network
assets over the previous period by analysing plant statistics available from
the reports presented above.
3.0 ASSET MANAGEMENT PLAN
All information generated from the asset management processes is collated
and issued in a document called the 'Asset Management Plan'. The 'Asset
Management Plan' is the end result of the involvement of various
departments and associated asset management processes described in the
previous paper. It aims to assess plant condition and estimate its remaining
|
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.