STEAM VALVE DRIVE CONTROL DEVICE

摘要

PROBLEM TO BE SOLVED: To surely close a steam valve having a constitution of storing a governing valve in an inside of a stop valve such that the governing valve is opened/closed coaxially and in the same direction, even when a failure is generated in a valve such as a servo valve or a dump valve. SOLUTION: When a differential pressure between a stop valve side oil pressure supply line 8a and a governing valve side oil pressure supply line 9a exceeds a predetermined value, a trip circuit 20 is provided which releases oil pressure in the governing valve side oil pressure supply line 9a to the stop valve side oil pressure supply line 8a to thereby reduce the oil pressure.