Protective relays are used to protect electric equipment such as motors and generators from electric faults. As an analogy, they are the circuit breakers in your house. Digital protective relays provide a higher level of reliability, more functionality, and the ability to provide direct integration into multiple devices including SCADA compared to the older mechanical protective relays. Consequently, digital protective relays are an integral part of Smart Grid, grid modernization, use of renewables, etc.
When a relay fails to operate as designed, major equipment damage or failure can occur with little opportunity to prevent the event because it was the protection that was compromised. Aurora was an example of using the relays as the attack vector to damage all alternating current (AC) equipment connected to the substation using those relays. Because of the importance of digital protective relays, DOE has spent large sums of money on R&D to make digital protective relays more cyber secure.
By Joe Weiss
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