Abstract: In a prime mover, an improved control system is provided for accelerating and decelerating the prime mover through periods of critical operation.

Abstract: In the control of prime movers, automatic and manually generated input signals should be able to be entered into the control system without undue control disturbance or perturbation. Likewise should an automatic signal fail, the switch to a last valid signal prior to entry into a manual mode is also desirable. An analog-digital hybrid circuit is described which includes a memory, storage, timing and manual input portions as well as certain select A or B circuits which allow for bumpless transfer between automatic manual and memory modes of operation.

Abstract: The disclosure sets forth trip circuitry for a rotating shaft machine which includes redundant overspeed protection and means for testing the overspeed protection circuit while the machine remains in operation. Moreover, further protective circuitry is provided for detecting a failure in the speed sensing system. The overspeed protection and the speed sensing failure circuit are each connected to a relay system which may actuate a trip servo valve to a closed position.