Patent ID: 8753067

Claim:
A steam valve apparatus, comprising: a steam valve passing or blocking a steam to a turbo machine; a piston operated by a hydraulic liquid to open or close the steam valve; a hydraulic cylinder including an internal space sectioned into a first chamber and a second chamber by the piston, the first chamber being on an open side of the steam valve, and the second chamber being on a close side of the steam valve; a hydraulic control valve to control supply of the hydraulic liquid to the first chamber; a first passage to supply the hydraulic liquid to the hydraulic control valve; a second passage connecting the first chamber and the second chamber; a third passage to drain the hydraulic liquid from the second chamber; an electromagnetic valve switched between a first state and a second state based on an input of a signal; a first cartridge valve opening the first passage when the electromagnetic valve is in the first state, and closing the first passage when the electromagnetic valve is in the second state; and a second cartridge valve closing the second passage when the electromagnetic valve is in the first state, and opening the second passage to drain the hydraulic liquid in the first chamber via the second passage, the second chamber, and the third passage when the electromagnetic valve is in the second state, wherein the electromagnetic valve includes: a first port to which the hydraulic liquid is supplied; a second port from which the hydraulic liquid is drained; a third port connected to a control port of the first cartridge valve; and a fourth port connected to a control port of the second cartridge valve, the first and fourth ports are connected and the second and third ports are connected when the electromagnetic valve is in the first state, and the first and third ports are connected and the second and fourth ports are connected when the electromagnetic valve is in the second state.