Trip system for steam turbine

A trip system for a steam turbine that closes a trip-and-throttle valve and a control valve of a steam turbine in an emergency, the trip system comprising:

• an emergency shut-off device that shuts off supply of control oil for the trip-and-throttle valve and the control valve to close the trip-and-throttle valve and the control valve;
• and
• a drain device that includes a plurality of solenoid valves connected in parallel and drains the control oil by opening the solenoid valves, wherein the emergency shut-off device includes:
• a cylinder;
• a piston that slides in the cylinder;
• a spring that applies biasing force to the piston;
• a plurality of piston valves provided to the piston;
• and
• a plurality of chambers formed by the piston valves,
• the plurality of chambers includes:
• a transfer chamber that moves the piston from a normal position during normal operation to an emergency position when the control oil is drained from the transfer chamber,
• a supply chamber that supplies the control oil to the control valve in normal operation,
• a control-valve drainage chamber that drains the control oil from the control valve during the emergency, and
• a trip-and-throttle-valve drainage chamber that drains the control oil from the trip-and-throttle valve during the emergency, and
• piping through which the control oil is supplied includes:
• a first piping connected to the supply chamber;
• and
• a second piping that passes through an orifice and is connected to the drain device, the transfer chamber, the trip-and-throttle-valve drainage chamber, and the trip-and-throttle valve so that the drain device, the transfer chamber, the trip-and-throttle-valve drainage chamber, and the trip-and-throttle valve are in parallel.