Abstract: A prime mover which is equipped with an electric speed governor may produce adequate electrical power output through a shaft driven permanent magnet alternator to run the electric speed governor. However, initially an auxiliary power source must be connected to the electric governor until the permanent magnet alternator becomes self-sustaining. The present invention is an electrical circuit which will automatically provide start-up power from an auxiliary source and then switch to the permanent magnet alternator. Certain safety interlocks are provided in case of speed pick-up failure.

Abstract: In the field of closed loop control systems, a reference signal input is compared with a feedback signal to provide an error signal which then initiates corrective action until the feedback signal duplicates the reference signal. Hence, the reference signal may be appreciated as the set point at which the control system should operate. The disclosure relates to a manual input reference signal circuit which may be used to input a desired reference speed signal into a control system circuit for a prime mover. Provision is made for both local and remote manual signal input and priority logic is included for selecting the most appropriate reference signal. Inhibit logic dictates the floor and ceiling for the range of prime mover 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.

Abstract: The reliability of any system can be enhanced by redundancy. In a turbomachine control system, increased reliability through redundancy is particularly desirable in view of the consequences of an unscheduled shutdown. One area of a turbomachine controls system which is particularly suited to redundant modeling is the speed control circuits. Speed pick-up probes may be subject to severe duty and are critical to the speed control of a turbomachine since they provide the speed feedback signal. The present invention is a solid state circuit which provides an output signal even if either one of two redundant speed feedback probes should fail. This circuit also allows probe replacement while the turbomachine remains in service.