General Purpose (GP) Relay

The General Purpose (GP) Relays function as the central logic processing unit of a locomotive's low-voltage control system. These relays are electromagnetic switches that orchestrate complex sequences, such as engine cranking, fuel delivery, and traction motor transitions, by opening or closing auxiliary circuits. They act as "gatekeepers" that provide essential safety interlocking, ensuring that high-power contactors only engage when specific conditions—like throttle position and brake status—are safely met.