Protection system for controller and control wiring induced under

Abstract

A protection system minimizing utilization equipment's exposure to, and power interruption resulting from, an under voltage condition in an electric power generating system includes generator current sensors, generator speed information, an exciter current sensor, voltage sensors, and a controller. The controller utilizes a voltage level detector which calculates an average voltage magnitude and generates a control signal when the average voltage magnitude drops below a threshold, and which monitors the peak value of each phase voltage and generates a lock out signal when any one of the phase voltages exceeds a threshold; a current detector which generates an enable signal when the magnitude of the highest phase of the generator current is less than a threshold; an exciter current detector which generates a second enable signal when the exciter current is outside an acceptable operating range; a generator speed monitor which generates a control signal when the generator speed is above a minimum regulation speed; protection logic which generates a protective trip signal; and breaker drivers which control the position of system breakers to isolate the fault and re-energize the system loads. The protection logic discriminates between an under voltage condition caused by an overload or a through fault on a main load bus, and one caused by a failure in the controller or associated wiring.