Turbine overspeed trip system with testing mechanism

Claim 2

A steam turbine overspeed trip system comprising: valve means adapted to control the flow of steam from a steam generator to the inlet of a steam turbine, a valve controller comprising a cylinder, a piston slidable in said cylinder, said piston and cylinder comprising an enclosed chamber of variable volume, means responsive to relative movement of said piston and cylinder for effecting opening and closing movement of said valve means, said opening and closing movements corresponding respectively to enlargement and contraction of the volume of said chamber, means urging said piston and cylinder relative to each other in a direction to effect closure of said valve means, a first port communicating with said chamber throughout the range of travel of the piston relative to the cylinder, means normally preventing flow of fluid outwardly from said chamber through said first port, a second port normally communicating with said chamber and arranged to be closed off when said piston and cylinder travel a part of the range of movement from the relative positions corresponding to a fully open condition of the valve means to the relative positions corresponding to a fully closed condition thereof, means for delivering a fluid under pressure into said chamber, means responsive to the turbine shaft speed for effecting an opening of said first port when the turbine shaft speed exceeds a predetermined limit, and manually operable means for preventing outward flow from said chamber through said first port and allowing fluid to flow from said chamber through said second port to allow a relative movement of said cylinder and piston through said part of said range.

Claim 3

A steam turbine overspeed trip system according to claim 1 in which said means normally preventing flow of fluid outwardly from said chamber through said first port comprises a fluid pressure-actuated pilot valve, and in which said means for delivering a fluid under pressure into said chamber comprises a restricted passage.

Claim 4

A steam turbine overspeed trip system comprising: valve means adapted to control the flow of steam from a steam generator to the inlet of a steam turbine, a valve controller comprising a cylinder, a piston slidable in said cylinder, said piston and cylinder comprising an enclosed chamber of variable volume, means responsive to relative movement of said piston and cylinder for effecting opening and closing movement of said valve means, said opening and closing movements corresponding respectively to enlargement and contraction of the volume of said chamber, means urging said piston and cylinder relative to each other in a direction to effect closure of said valve means, a first port communicaTing with said chamber throughout the range of travel of the piston relative to the cylinder, means normally preventing flow of fluid outwardly from said chamber through said first port, a second port normally communicating with said chamber and arranged to be closed off when said piston and cylinder travel a part of the range of movement from the relative positions corresponding to a fully open condition of the valve means to the relative positions corresponding to a fully closed condition thereof, and means normally preventing flow of fluid outwardly from said chamber through said second port means for delivering a fluid under pressure into said chamber, first and second valves connected in series, one end of said series of valves being connected to said means for delivering a fluid, and the interconnection between said valves being connected to said second port, said first valve being normally open and said second valve being normally closed, means responsive to the turbine shaft speed for effecting an opening of said second valve when the turbine shaft speed exceeds a predetermined limit, and manually operable means for closing said first valve, and opening said second valve, thereby allowing fluid to flow from said chamber through said second port and said second valve to allow a relative movement of said cylinder and piston through part of said range.

Claim 5

A steam turbine overspeed trip system comprising: valve means adapted to control the flow of steam from a steam generator to the inlet of a steam turbine, a valve controller comprising a cylinder, a piston slidable in said cylinder, said piston and cylinder comprising an enclosed chamber of variable volume, means responsive to relative movement of said piston and cylinder for effecting opening and closing movement of said valve means, said opening and closing movements corresponding respectively to enlargement and contraction of the volume of said chamber, means urging said piston and cylinder relative to each other in a direction to effect closure of said valve means, a first port communicaTing with said chamber throughout the range of travel of the piston relative to the cylinder, means normally preventing flow of fluid outwardly from said chamber through said first port, a second port normally communicating with said chamber and arranged to be closed off when said piston and cylinder travel a part of the range of movement from the relative positions corresponding to a fully open condition of the valve means to the relative positions corresponding to a fully closed condition thereof, and means normally preventing flow of fluid outwardly from said chamber through said second port means for delivering a fluid under pressure into said chamber, first and second valves connected in series, one end of said series of valves being connected to said means for delivering a fluid, and the interconnection between said valves being connected to said second port, said first valve being normally open and said second valve being normally closed, means responsive to the turbine shaft speed for effecting an opening of said second valve when the turbine shaft speed exceeds a predetermined limit, and manually operable means for closing said first valve, and opening said second valve, thereby allowing fluid to flow from said chamber through said second port and said second valve to allow a relative movement of said cylinder and piston through part of said range.

Claim 6

A steam turbine overspeed trip system according to claim 3 in which said second valve is a solenoid-operated valve having a solenoid arranged to effect opening of said valve when energized, and wherein said means responsive to the turbine shaft speed includes means for energizing said solenoid, and said manually operable means also includes means for energizing said solenoid.

Claim 7

A steam turbine overspeed trip system according to claim 3 wherein said first valve is a solenoid-operated valve including means maintaining said first valve in an opened condition except when said solenoid is energized.

Claim 8

A steam turbine overspeed trip system according to claim 3 including a switch having a pressure-responsive actuator and wherein said first valve is a three-way valve arranged to allow flow of fluid from said means for delivering a fluid when in an opened condition, and to block said flow and allow flow from said means for delivering a fluid to said pressure-responsive actuator when in a closed condition.

Claim 9

A steam turbine overspeed trip system comprising: first and second steam stop valves adapted to control the flow of steam from a steam generator to the inlet of a steam turbine, first and second fluid-actuated valve controllers, each arranged to control one of said stop valves, means responsive to the turbine shaft speed for operating said controllers simultaneously to effect full closure of both of said stop valves when the shaft speed exceeds a predetermined limit, and manually operable means for operating said controllers individually to effect partial closure of each of said stop valves.

Claim 10

A steam turbine overspeed trip system comprising: first and second steam stop valves adapted to control the flow of steam from a steam generator to the inlet of a steam turbine, first and second fluid-actuated valve controllers, each arranged to control one of said stop valves, means responsive to the turbine shaft speed for operating said controllers simultaneously to effect full closure of both of said stop valves when the shaft speed exceeds a predetermined limit, and manually operable means for operating said controllers individually to effect partial closure of each of said stop valves.