A defective lockout relay should be replaced with an exact duplicate, sometimes called what?

A defective lockout relay should be replaced with an exact duplicate, sometimes called what?

• A. Time-delay relay
• B. Impedance relay
• C. Magnetic relay
• D. Thermal relay

Answer: (B)

Replacing a defective lockout relay with an exact duplicate keeps the protection system’s timing and coordination intact. An impedance relay is a type of protective relay that relies on the measured impedance to decide when to trip and latch, so using an identical impedance relay ensures the same pickup and dropout settings, response time, and latch behavior as before. This preserves how the system responds to faults and avoids introducing changes that could cause miscoordination or unwanted trips. Other options reflect different operating principles—time-delay, magnetic, or thermal relays—and would not reproduce the same electrical response or coordination, which is why they aren’t the best fit for an exact duplicate.

Replacing a defective lockout relay with an exact duplicate keeps the protection system’s timing and coordination intact. An impedance relay is a type of protective relay that relies on the measured impedance to decide when to trip and latch, so using an identical impedance relay ensures the same pickup and dropout settings, response time, and latch behavior as before. This preserves how the system responds to faults and avoids introducing changes that could cause miscoordination or unwanted trips. Other options reflect different operating principles—time-delay, magnetic, or thermal relays—and would not reproduce the same electrical response or coordination, which is why they aren’t the best fit for an exact duplicate.