An EMP, also known as a transient electromagnetic disturbance, creates a burst of electromagnetic energy that spreads over a range of frequencies and can damage or disrupt the function of electronic equipment. EMPs can result in strong electric and magnetic fields, causing voltages and currents to be induced on conductors.
EMP effects are similar to any harsh electromagnetic event found in power systems, such as lightning strikes, radio frequency interference (RFI), and high-voltage surge events. However, the effects can have greater severity and can occur at various frequencies. Of concern are EMP events that couple voltage transients to conductors that connect equipment in the substation yard to the control enclosure.
There are two categories of EMP risk:
There are concerns that equipment used to protect and manage the operation of the power network is vulnerable to HEMP and IEMI events with the potential to disrupt the safe operation of the power system. SEL addresses the concerns in “Understanding Design, Installation, and Testing Methods That Promote Substation IED Resiliency for High-Altitude Electromagnetic Pulse Events." SEL protective relays and other SEL products are HEMP resilient in power substations.