Steam pressure control device for nuclear power plant

Purpose: To always keep the pressure controller outputs of two systems within a predetermined range even if a slight error is contained in the outputs of a pair of pressure detectors by automatically varying and controlling the bias state with an automatic bias control circuit. Constitution: The output detected by a pressure detector is input to a deviation detector, is added to or subtracted from the output signal from the pressure detector and the output signal from a bias setting unit, is introduced as a deviation signal through a pressure regulator output to a high value priority circuit, the system signal being high level is selected and is applied to a servo mechanism for regulating the opening of a turbine control valve. On the other hand, the deviation signal from the pressure regulator output unit is added or subtracted, differential output is produced therefrom, is input through a delay circuit to a discriminator, which thereby judges whether it falls within an allowable range or not. If not, the output is applied to a motor control circuit, a bias setting unit is variably controlled, and the set bias value is varied. (Yoshino, Y.)