BACKGROUND 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to testing systems, and more particularly to a temperature testing system for a power supply. 
         [0003]    2. Description of Related Art 
         [0004]    A power supply is very important in a computer for supplying power to each part of the computer and ensuring normal running of the parts in the computer. If the power supply does not function properly, the computer will not run normally. Therefore, the working parameters of the power supply need to be tested during design, manufacture, and testing of the computer. 
         [0005]    In a temperature testing system for a power supply, it is common to test under a variety of conditions to ensure ability of the power supply to operate properly in different working states. It usually takes twelve hours to test a power supply in the temperature testing system, and testing conditions need to be manually changed every two hours. This process is very complex for the testing operators, and adds to the time and cost of testing. 
         [0006]    What is needed, therefore, is a temperature testing system for a power supply with the testing conditions being changed automatically. 
       SUMMARY 
       [0007]    A testing system for testing a temperature of a power supply includes a testing chamber, a control switch, an electrical load, an AC source, and a PLC. The power supply has a voltage choice switch for switching the power supply to operate at a first voltage or a second voltage. The testing chamber is configured for receiving the power supply therein. The testing chamber is configured for selectively providing a first or a second ambient temperature and supplying a testing environment for the power supply. The control switch is configured for switching the power supply to operate between a standby state and an operational state. The electrical load electrically is connected to the power supply, for functioning as a testing load for the power supply. The AC source is electrically connected to the power supply. The AC source is configured for outputting the first voltage or the second voltage to the power supply. The PLC is configured for controlling switching states of the voltage choice switch and the control switch in a manner such that the power supply selectively operates in one of combined switching states of the voltage choice switch and the control switch. 
         [0008]    Other advantages and novel features of the present invention will become more apparent from the following detailed description of a preferred embodiment when taken in conjunction with the accompanying drawings, in which: 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a configuration diagram of a testing system for a power supply in accordance with a preferred embodiment of the present invention; 
           [0010]      FIG. 2  is a chart depicting a timeline of the changing testing conditions in the testing system; 
           [0011]      FIG. 3  is a wiring diagram of a PLC in the testing system; and 
           [0012]      FIG. 4  is a working flow chart of the PLC in the testing system. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    Referring to  FIG. 1 , a temperature testing system for a power supply  40  of an embodiment of the present invention is shown. The power supply  40  may be used in for example a computer. The temperature testing system includes a testing chamber  10  for receiving the power supply  40 , a testing board  20 , an electrical load  50 , an Alternating Current (AC) source  60 , a control device  80  connected to the electrical load  50  and the AC source  60  respectively, and a Programmable Logic Controller (PLC)  30 . 
         [0014]    The power supply  40  is connected to the AC source  60  for receiving an input voltage from the AC source  60 . The power supply  40  is also connected to the electrical load  50  via the testing board  20 . A voltage choice (115/230V) switch is mounted on the power supply  40 . In this embodiment, when the 115/230V switch is closed, the input voltage of the power supply  40  from the AC source  60  is 115V; when the 115/230V switch is open, the input voltage of the power supply  40  from the AC source  60  is 230V. The testing chamber  10  is used for simulating a working environment of the power supply  40 , and can be switched between two different states: a low temperature state when a computer is in standby condition, and a high temperature state when a computer is running. A signal control switch (PS-ON switch) for controlling a PS-ON (Power Supply-On) signal from the power supply  40  is mounted on the testing board  20 . When the PS-ON switch is closed, the power supply  40  is running; when the PS-ON switch is open, the power supply  40  is on standby. The electrical load  50  is a testing device for testing voltage, current and so on of power supplies. The electrical load  50  includes a plurality of input interfaces, and can simulate a load to the power supply  40  for testing. In this embodiment, the electrical load  50  includes three loads: a standby load, a first full load, and a second full load; the control device  80  is a CHROMA  8200  device. The control device  80  communicates with the electrical load  50  and the AC source  60  via the General-Purpose Interface Bus (GPIB) for automatically controlling changing among the three loads and automatically controlling the input voltage output by the AC source  60  to switch between 230V and 115V. The PLC  30  is connected to the power supply  40 , the AC source  60 , and the testing board  20 , for detecting whether the power supply  40  is operating normally and automatically controlling openings or closings of the 115/230V switch and the PS-ON switch. 
         [0015]    Referring to  FIG. 2 , a timing chart of the changing testing conditions in the testing system is shown. In the temperature testing system for the power supply  40 , it usually takes twelve hours (12 H) to complete, and some of the testing conditions need to be changed every two hours. From 0 H˜2 H, the input voltage of the power supply  40  output by the AC source  60  is 230V, the 115/230V switch is open, the electrical load  50  is set to standby load, the PS-ON switch is open, and the testing chamber  10  is in the low temperature state. From 2 H˜4 H, the electrical load  50  is set to first full load, the PS-ON switch is closed, the testing chamber  10  is in the high temperature state, and other testing conditions remain the same. From 4 H˜6 H, the electrical load  50  is set to second full load, and other testing conditions remain the same as from 2 H˜4 H. From 6 H˜8 H, the input voltage of the power supply  40  is set to 115V, the 115/230V switch is closed, and other testing conditions remain the same as from 4 H˜6 H. From 8 H˜10 H, the electrical load  50  is set to first full load, and other testing conditions remain the same as from 6 H˜8 H. From 10 H˜12 H, the electrical load  50  is set to standby load, the PS-ON switch is open, the testing chamber  10  is in the low temperature state, and other testing conditions remain the same as from 8 H˜10 H. The temperature data of the power supply  40  and the components therein are stored in a data base accessible by testing operators at the end of each two hour testing period. 
         [0016]    Referring to  FIG. 3 , a wiring diagram of the PLC  30  in the testing system is shown. Two output terminals of the AC source  60  are connected to the input terminal of the power supply  40  through a switch KM. The two output terminals of the AC source  60  are connected to each other through a resistor R 1  and two light emitting diodes (LEDs) D 1 , D 2  connected in parallel. The LEDs D 1 , D 2  are positioned adjacent to each other. A photoresistor R 2  for sensing light is positioned adjacent the LEDs D 1 , D 2 . Two terminals of the resistor R 2  are respectively connected to the input terminals X 0  and COM of the PLC  30 . A switch K 1  is connected between the input terminals X 0  and COM of the PLC  30 . A +5 Vsb (stand by) assistant voltage signal output by the power supply  40  is connected to the input terminals X 1  and COM of the PLC  30  through a resistor R 3  and a photoelectric coupler  31 . A switch K 2  is connected between the input terminals X 1  and COM of the PLC  30 . A PG (Power Good) power voltage signal output by the power supply  40  is connected to the input terminals X 2  and COM of the PLC  30  through a resistor R 4  and a photoelectric coupler  33 . A switch K 3  is connected between the input terminals X 0  and COM of the PLC  30 . A switch K 4  is connected between the output terminals Y 0  and COM 0  of the PLC  30 . The output terminal Y 0  is connected to the PS-ON switch via a node  11 . The output terminal COM 0  is connected to ground via a node  13 . A diode D 3  is connected between the nodes  11  and  13 . The output terminals Y 2 , Y 3 , and Y 4  of the PLC  30  are respectively connected to the switches K 5 , K 6 , and K 7 . The switches K 5 , K 6 , and K 7  are also connected to an output terminal COM 2  of the PLC  30 . The output terminal Y 2  is also connected to a terminal  32  through a lamp  35  and a node  12 . The output terminal Y 3  is connected to the node  12  through a node  14 , and a node  15 , and the node  14  is also connected to the node  15  through an LC module  18 , and a node  17 . The switch KM is also connected between the node  14  and the node  15 . The output terminal Y 4  is connected to the node  17  through a relay J. The output terminal COM 2  is also connected to a terminal  34 . A voltage from the AC source is inputted across the terminals  32  and  34 . When the LEDs D 1  or D 2  emit light, the switch K 1  will be closed under the control of the photoresistor R 2 . When the +5 Vsb assistant voltage signal is input normally, the switch K 2  will be closed under the control of the photoelectric coupler  31 . When the PG signal is input normally, the switch K 3  will be closed under the control of the photoelectric coupler  33 . The switch K 4  is used for controlling opening or closing of the PS-ON switch. The switches K 5  and K 6  remain closed when the power supply  40  operates normally. The switch K 7  controls opening or closing of the relay J to realize opening or closing of the 115/230V switch. 
         [0017]    Referring to  FIG. 4 , a working flow chart of the PLC  30  in the testing system is shown. If the PLC  30  detects that the input voltage to the power supply  40  is 230V and the electrical load  50  is on the standby load, the switch K 4  will be opened, the switch K 5  will be closed, the switch K 6  will be closed, and the switch K 7  will be opened under the control of the PLC  30 . If the switch K 2  opens at this time, the testing will stop and the testing operators will check fault of the testing system, if the switch K 5  or K 6  is opened, a fault will be indicated in the power supply  40 . 
         [0018]    If the PLC  30  detects that the input voltage to the power supply  40  is 230V and the electrical load  50  changes to the first full load, the switch K 4  will be closed, the switch K 5  will be closed, the switch K 6  will be closed, and the switch K 7  will be opened under the control of the PLC  30 . If the switch K 2  or K 3  opens, the testing will stop and the testing operators will check fault of the testing system, if the switch K 5  or K 6  is opened, a fault will be indicated in the power supply  40 . 
         [0019]    If the PLC  30  detects that the input voltage to the power supply  40  is 230V and the electrical load  50  changes to the second full load, the switch K 4  will be closed, the switch K 5  will be closed, the switch K 6  will be closed, and the switch K 7  will be opened under the control of the PLC  30 . If the switch K 2  or K 3  opens, the testing will stop and the testing operators will check fault of the testing system, if the switch K 5  or K 6  is opened, a fault will be indicated in the power supply  40 . 
         [0020]    In this embodiment, it usually takes 5 ms delay when the input voltage to the power supply  40  changes from 230V to 115V, and then the switch K 4  will be opened, the switch K 5  will be closed, the switch K 6  will be opened, and the switch K 7  will be closed under the control of the PLC  30 . In this delay time, the testing will not stop and the testing operators know that it is only a testing process. 
         [0021]    If the PLC  30  detects that the input voltage of the power supply  40  changes to 115V and the electrical load  50  is on the second full load, the switch K 4  will be closed, the switch K 5  will be closed, the switch K 6  will be closed, and the switch K 7  will be closed under the control of the PLC  30 . If the switch K 2  or K 3  opens, the testing will stop and the testing operators will check fault of the testing system, if the switch K 5  or K 6  is opened, a fault will be indicated in the power supply  40 . 
         [0022]    If the PLC  30  detects that the input voltage of the power supply  40  is 115V and the electrical load  50  changes to the first full load, the switch K 4  will be closed, the switch K 5  will be closed, the switch K 6  will be closed, and the switch K 7  will be closed under the control of the PLC  30 . If the switch K 2  or K 3  opens, the testing will stop and the testing operators will check fault of the testing system, if the switch K 5  or K 6  is opened, a fault will be indicated in the power supply  40 . 
         [0023]    If the PLC  30  detects that the input voltage of the power supply  40  is 115V and the electrical load  50  changes to the standby load, the switch K 4  will be opened, the switch K 5  will be closed, the switch K 6  will be closed and the switch K 7  will be closed under the control of the PLC  30 . If the switch K 2  is opens, the testing will stop and the testing operators will check fault of the testing system, if the switch K 5  or K 6  is opened, a fault will be indicated in the power supply  40 . When the testing is finished, the testing operators can find and register the testing data in the data base. 
         [0024]    Therefore, in the temperature testing system for the power supply  40 , it is needless to change the testing conditions manually: the input voltage from the AC source  60  and the state of the electrical load  50  will be changed through controlling of the control device  80 ; the openings or closings of the 115/230V switch and the PS-ON switch will be under the control of the PLC  30 ; and the temperature of the testing chamber  10  will be changed automatically. 
         [0025]    It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.
A testing system for a power supply ( 40) includes a testing chamber ( 10), a control switch, an electrical load ( 50), an AC source ( 60), and a PLC ( 30). The power supply has a voltage choice switch. The testing chamber receives the power supply therein. The testing chamber provides a first or a second ambient temperature and supplies a testing environment for the power supply. The control switch switches the power supply to operate between a standby state and an operational state. The electrical load is connected to the power supply. The AC source is connected to the power supply. The AC source outputs the first voltage or the second voltage to the power supply. The PLC controls switching states of the voltage choice switch and the control switch in a manner such that the power supply selectively operates in one of combined switching states of the voltage choice switch and the control switch.