High voltage (HV) transformer units make up less than 3% of transformers in U.S. power substations, but they carry 60% or more of the nation's electricity. Because they serve as vital transmission network nodes and carry bulk volumes of electricity, HV transformers are critical elements of the nation's electric power grid. For reasons discussed below, however, HV transformers are considered by many experts to be the most vulnerable to intentional damage from malicious acts. Congressional Interest

Congress has long been concerned about grid security in general, but recent security exercises, together with a 2013 physical attack on transformers in Metcalf, CA, have focused congressional interest on the physical security of HV transformers, among other specific aspects of the grid. They have also prompted new grid security initiatives by utilities and federal regulators. Legislative proposals including the Enhanced Grid Security Act of 2015 ( S. 1241 ), the Critical Electric Infrastructure Protection Act ( H.R. 2271 ), the Terrorism Prevention and Critical Infrastructure Protection Act of 2015 ( H.R. 85 ), a House bill to establish a strategic transformer reserve program ( H.R. 2244 ), and the Grid Modernization Act of 2015 ( S. 1243 ) would expand these activities by strengthening federal efforts to prevent or recover from a physical attack on the U.S. grid. Sector Initiatives for HV Transformer Security

Over the last decade or so the electric utility industry and government agencies have engaged in a number of initiatives to secure HV transformers from physical attack and to improve recovery in the event of a successful attack. These initiatives include coordination and information sharing, spare equipment programs, security standards, grid security exercises, and other measures discussed below. NERC Physical Security Regulations

On March 7, 2014, FERC ordered NERC to submit to the commission within 90 days proposed reliability standards requiring certain transmission owners "to take steps or demonstrate that they have taken steps to address physical security risks and vulnerabilities related to the reliable operation" of the power grid. On November 20, 2014, FERC approved the proposed standard, with minor changes, as NERC's new Physical Security Reliability Standard (CIP-014-1). Development, documentation, and implementation of physical security plans to protect critical facilities; and
R6. As the standards discussed in the previous section suggest, there has been some level of physical security investment and an increasing refinement of grid security practices across the electric power sector for at least the last 15 years. As the electric power industry and federal agencies continue their efforts to improve the physical security of critical HV transformer substations, Congress may consider several key issues as part of its oversight of the sector. There is widespread agreement among government, utilities, and manufacturers that HV transformers in the United States are vulnerable to terrorist attack, and that such an attack potentially could have catastrophic consequences. But the most serious, multi-transformer attacks could require acquiring operational information and a certain level of sophistication on the part of potential attackers. Consequently, despite the technical arguments, without more specific information about potential targets and attacker capabilities, the true vulnerability of the grid to a multi-HV transformer attack remains an open question. As Congress continues its examination of physical security policy, maintaining an integrated perspective on prevention, recovery, and resilience may help to promote an effective balance among industry investment, regulatory requirements, and federal oversight.
The U.S. electric power grid consists of over 200,000 miles of high-voltage transmission lines and hundreds of large transformer substations. High voltage (HV) transformer units make up less than 3% of U.S. transformers, but they carry 60%-70% of the nation's electricity. Because they serve as vital nodes, HV transformers are critical to the nation's electric grid. HV transformers are also the most vulnerable to damage from malicious acts.
For more than 10 years, the electric utility industry and government agencies have engaged in activities to secure HV transformers from physical attack and to improve recovery in the event of a successful attack. These activities include coordination and information sharing, spare equipment programs, security standards, security exercises, and other measures. There has been some level of physical security investment and an increasing refinement of voluntary security practices across the electric power sector for at least the last 15 years. However, recent grid security exercises, together with a 2013 physical attack on transformers in Metcalf, CA, have changed the way grid security is viewed and have focused congressional interest on the physical security of HV transformers. They have also prompted new grid security efforts by utilities and regulators.
On November 20, 2014, the Federal Energy Regulatory Commission (FERC) approved a new mandatory Physical Security Reliability Standard (CIP-014-1) proposed by the North American Electric Reliability Corporation (NERC). The new standards require certain transmission owners "to address physical security risks and vulnerabilities related to the reliable operation" of the power grid by performing risk assessments to identify their critical facilities, evaluate potential threats and vulnerabilities, and implement security plans to protect against attacks. Legislative proposals would expand federal efforts to prevent or recover from a physical attack on the U.S. grid. These include the Enhanced Grid Security Act of 2015 (S. 1241), the Critical Electric Infrastructure Protection Act (H.R. 2271), the Terrorism Prevention and Critical Infrastructure Protection Act of 2015 (H.R. 85), a House bill to establish a strategic transformer reserve program (H.R. 2244), and the Grid Modernization Act of 2015 (S. 1243).
There is widespread agreement among government agencies, utilities, and manufacturers that HV transformers in the United States are vulnerable to terrorist attack, and that such an attack potentially could have catastrophic consequences. But the most serious, multi-transformer attacks could require acquiring operational information and a certain level of sophistication on the part of potential attackers. Consequently, despite the technical arguments, without more specific information about potential targets and attacker capabilities, the actual risk of a multi-HV transformer attack remains an open question. As the electric power industry and federal agencies continue their efforts to improve the physical security of critical HV transformer substations, Congress may consider several issues as part of its oversight of the sector: identifying critical transformers, confidentiality of critical transformer information, adequacy of HV transformer protection, quality of federal threat information, recovery from HV transformer attacks, and the overall resiliency of the grid. Maintaining an integrated perspective on prevention, recovery, and resilience may help to promote an effective balance among industry investment, regulatory requirements, and federal oversight.