Abstract: Unnecessary fast valving action for load loss protection in a steam turbine generator system induced by partial transducer failure is minimized by the disclosedmethods and apparatus. Upon the occurrence of a mismatch between reheat pressure and electrical output, the interceptor valve is closed momentarily to interrupt the flow of steam to the low-pressure turbine and prevent overspeed. The valve cannot be closed again for a predetermined interval. If the mismatch is not corrected by the one fast valving action, a transducer has failed and further closing of the interceptor valve, except for a full load loss, is precluded until corrective action is taken. The faulty transducer is singled-out by comparing one of the transducer signals with the impulse pressure which is also an indication of the actual operating level of the turbine.

Abstract: A combined digital computer/analog control system for operating a boiling water reactor steam turbine power plant, wherein the digital computer provides a throttle pressure setpoint, speed error and load demand for controlling the plant depending upon the operational states of the system, is disclosed. The analog portion of the system also controls the plant in cooperation with the digital computer for certain operational states and conditions when the digital computer is in operation; and the analog system alone controls the plant when the digital computer is out of service. The transfer between such control is effected depending upon the operational states of the system and certain of the components therein. The system also includes in the digital computer portion, the provision for preventing a load demand which is outside the limits of the reactor circulation system when the reactor is in a state of automatic operation.

Abstract: A combined digital computer/analog control system for operating a boiling water reactor-steam turbine-power plant wherein one of two analog throttle pressure controllers is used for controlling the inlet and bypass valves. One of the pressure controllers is biased to provide a higher signal than the other; and such nonbiased controller is the one selected to control the valves. Each controller includes a pressure transducer, a summing device and amplifier, and a lead/lag circuit together with the appropriate power supply.A failure detection system is used to switch the controllers from automatic to manual when a predetermined combination of controller components becomes defective. Also, such system is so organized that a transducer failure for one controller causes the other controller to assume control regardless of whether such failure results in a higher or lower than proper signal.