TURBINE OVER-SPEED PREVENTING DEVICE

PURPOSE:To prevent the disturbance to an electric power system by delaying the speed of response in a control circuit which operates a regulating valve to close at the time of sudden increase of effective power in a turbine over-speed preventing device so that the closing operation of the regulating valve in response to the sudden fluctuation of electric power can be prevented. CONSTITUTION:An electric power detector 36 is provided in the output side of a generator 16 which is driven by a turbine 14, and the output of this detector is input to a comparator 86 via a high gain amplifier 80, an integrator 82 and an inversion amplifier 84, and then the signal II is compared with the signal I. The open or shut of an over-speed preventing solenoid valve 28 is controlled by driving an auxiliary relay 88 through the output III of the comparator 86. Thus, the over-speed preventing solenoid valve 28 is not excited and does not perform close operation for the increase of output of the generator 16 by setting the time constant of the integrator 82 at a larger value. Accordingly, unnecessary disturbance to an electric power system can be prevented.