29, each line has an overcurrent relay that protects the line. In electrical engineering, a protective relay is a relay device designed to trip a circuit breaker when a fault is detected. These relays are self-contained & compact devices that detect abnormal conditions occurring within the electrical circuits by measuring the. Thermostats, Pressure Switches, and Other Electric Control Devices contacts are usually made of. the easiest faults to diagnose with a contactor are usually problems with the. the pilot duty overload breaks. molten alloy relay - ratchet. Differential current protection, much like a ground-fault interrupter (GFI), measures incoming and exiting current from all three phases, stopping the circuit in case of any imbalance, no matter how long it persists.
[PDF Version]