Safety protection device of plant safety protection system

摘要

PURPOSE: To realize a reliable safety protection device having high velocity for system answering and capable of detecting failures in an early stage. ;CONSTITUTION: Trip signals operating a safety protection device are outputted from comparators D when an output signal from each of sensors S is in excess of reference value, OR operations, etc., of the trip signals from the comparators D are made by an operating means 52, signals from an operation result by the operating means 52 are converted into signals of reference frequency, and the reference frequency signals are transmitted to a fail safe circuit 12 through transmission systems 55, 57 and 56. Frequency of input signals is monitored by the fail safe circuit 12, the input signals are the input signals to a transformer when the frequency is in a reference range, and the input to the transformer is cut off when the frequency deviates from the reference range. The fail safe circuit is so constituted that switching elements controlling operation of load are driven by d.C. signals rectifying the output of the transformer.;COPYRIGHT: (C)1994,JPO&Japio