In the beginning, there was the electromechanical relay. With the advance of technology, solid state and later microprocessor relays began to be installed in substations, but while they offered tremendous improvements over their predecessors, they also came with at least one major drawback. Modern relays, also called intelligent electronic devices (IEDs), don’t require regular testing and calibration, and today’s IEDs can do in the space of a bread box what it once took a series of eight 8-foot-by-3-foot panels to do. Their Achilles heel, though, is a susceptibility to electromagnetic interference (EMI).

‘Hardening’ the Power Substation
By Bob Fesmire, ABB Inc.

Overcoming this vulnerability was perhaps the genesis of the present-day concept of “substation hardening,” though that term is now often used to refer to protection against cyber attack. The recent obsession with cyber security is well-founded—the threat is real, and the utility industry’s reliance on “security by obscurity” no longer holds, as arcane proprietary systems are replaced with widely used commercial products and open standards. However, the likelihood of

Equipment like the managed field switch pictured here are engineered specifically as “hardened” substation devices.