| 摘要 |
In a steam turbine control system, the mechanical/hydraulic input to a mechanical control link within a servo enclosure controlling the steam supply valves to the turbine is replaced by an electrical/hydraulic control system while retaining all mechanical/hydraulic connections between the servo enclosure and the steam valves. A hydraulic cylinder is coupled to a control link in the servo enclosure which operates the steam valves. The cylinder is actuated by a servo control valve for modulating the flow of steam to the turbine. A fast trip valve forms part of the hydraulic fluid supply to the piston and is movable in response to a cutoff of hydraulic pressure fluid to the shut-off valve to shift and deadend the hydraulic fluid supply to the piston whereby, in response to a system upset, the shut-off valve instantaneously stops the supply of hydraulic fluid to the piston and thereby instantaneously actuates the steam valves to preclude flow of steam to the turbine.
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