System and method for operating a steam turbine with dual hydraulic independent overspeed protection especially adapted for a nuclear reactor powered steam turbine

Claim 1

An electric power generation system comprising: a steam turbine system having at least one high pressure and at least one low pressure turbine, a generator rotated by the turbine, means for valving, said valving means regulating a flow of steam through said steam turbine system, means for actuating said means for valving, means for measuring the rotational velocity of said steam turbine system, means for independently measuring the rotational velocity of said steam turbine system, said independent measuring means including at least three measuring channel means, means for determining whether a predetermined number of said channel means have representations of turbine system conditions corresponding to predetermined conditions, means for deactivating said actuator means, a dump oil receiver tank, said means for deactivating comprising dump valve means with at least two dump valves spaced in a predetermined relationship one from the other for dumping hydraulic fluid of said actuating means into said dump oil receiver tank, and means for connecting said dump valves to said actuator means, said connecting means being spaced in a predetermined relationship one from the other whereby an extremely low probability of simultaneous damage to both of said dump valves and associated connecting means results.

Claim 9

A method for independently preventing overspeed in a steam turbine generating system resulting from partial or total load losses, said steam turbine generating system comprising at least one high pressure turbine, at least one low pressure turbine; and control, interceptor and governor valves associated therewith, an electrical generator rotated by said turbines, a breaker connected between said generator and an electric load, actuators for actuating said valves, a first transducer for transducing the rotational veLocity of said steam turbine into an electrical signal, a controller receiving signals from said first transducer and transmitting signals to said actuators for controlling the position of said actuators and said valves, second transducing means for independently transducing the rotational velocity of said steam turbine into an electrical signal, said second transducing means providing a plurality of independent speed signals, a speed channel being provided for each speed signal, a check circuit included in each signal channel, control logic connected to said signal channels, two dumping signal channels including two separate dump valves independently actuated and connected to said actuators for dumping hydraulic fluid contained in said actuators, said dump valves and pipes connected thereto shielded, including the steps of: transducing speed of said turbine into a plurality of independent electrical signals; checking said signals against predetermined conditions; determining whether a predetermined number of said signals check against said predetermined conditions of the immediately preceding step; activating each of said dump valves upon determining whether a predetermined number of said signal channels do not correspond to said predetermined conditions; actuating each of said separate dump valves on each of said actuators using an independent signal derived from said control logic; shielding the pipes connected to said dump valves from missiles.

Claim 10

A method for independently preventing overspeed in a steam turbine generating system resulting from partial or total load losses, said steam turbine generating system comprising at least one high pressure turbine, at least one low pressure turbine; and control, interceptor and governor valves associated therewith, an electrical generator rotated by said turbines, a breaker connected between said generator and an electric load, actuators for actuating said valves, a first transducer for transducing the rotational veLocity of said steam turbine into an electrical signal, a controller receiving signals from said first transducer and transmitting signals to said actuators for controlling the position of said actuators and said valves, second transducing means for independently transducing the rotational velocity of said steam turbine into an electrical signal, said second transducing means providing a plurality of independent speed signals, a speed channel being provided for each speed signal, a check circuit included in each signal channel, control logic connected to said signal channels, two dumping signal channels including two separate dump valves independently actuated and connected to said actuators for dumping hydraulic fluid contained in said actuators, said dump valves and pipes connected thereto shielded, including the steps of: transducing speed of said turbine into a plurality of independent electrical signals; checking said signals against predetermined conditions; determining whether a predetermined number of said signals check against said predetermined conditions of the immediately preceding step; activating each of said dump valves upon determining whether a predetermined number of said signal channels do not correspond to said predetermined conditions; actuating each of said separate dump valves on each of said actuators using an independent signal derived from said control logic; shielding the pipes connected to said dump valves from missiles.