All governors have some sort of safety shutdown mechanism to operate automatically or manually to close the wicket gates in case of emergency. The device is usually controlled by a solenoid. In most cases, a weighted arm that is connected to the gate limit mechanism is held in place by the solenoid. If the trip is initiated, either automatically or manually, the solenoid is de- energized, dropping the weight, causing the gate limit to go to zero. A few installations have shutdown solenoids that are designed so that they must be energized to trip. Typically, there.
