Abstract: A hydraulic drive valve monitoring device includes a determination part and an alarm part. The determination part is configured to determine whether there is a sign of failure in the hydraulic drive valve device based on a result of comparison between a transition of a working fluid pressure measurement value obtained by measuring a pressure of the working fluid flowing into the valve body part and a transition of a working fluid pressure reference value set for the pressure of the working fluid flowing into the valve body part, when the opening degree of the valve body part is changed. The alarm part is configured to output an alarm when the determination part determines that there is a sign of failure in the hydraulic drive valve device.

Abstract: A steam turbine valve drive apparatus in an embodiment includes a piston, a cylinder, a bidirectional pump, a servo motor, and a quick closing mechanism. The cylinder houses the piston in an inner space thereof, the inner space being partitioned by the piston into a first hydraulic chamber and a second hydraulic chamber. The quick closing mechanism executes a quick closing operation of closing the steam valve unit more quickly than the closing operation. Here, the quick closing mechanism executes the quick closing operation by feeding the working oil accumulated in an accumulator to the second hydraulic chamber and draining the working oil from the first hydraulic chamber.

Abstract: A steam turbine valve drive apparatus in an embodiment includes a piston, a cylinder, a bidirectional pump, a servo motor, and a quick closing mechanism. The cylinder houses the piston in an inner space thereof, the inner space being partitioned by the piston into a first hydraulic chamber and a second hydraulic chamber. The quick closing mechanism executes a quick closing operation of closing the steam valve unit more quickly than the closing operation. Here, the quick closing mechanism executes the quick closing operation by feeding the working oil accumulated in an accumulator to the second hydraulic chamber and draining the working oil from the first hydraulic chamber.