Frequency Simulator Switch, S4
The frequency Simulator Switch is a single-pole, double-throw, switch with
momentary contacts used for maintenance purposes only. It functions to increase or
decrease the engine’s speed by sending a signal to the appropriate contact on the
engine’s ECM. When the engine’s speed is increased, the generator’s output
frequency is also increased, and visa versa. This switch is used to ensure the
generator control module (GCM) causes the output contactor(s) to open anytime the
frequency goes over 420 Hz or falls under 380 Hz.