Turbine speed control

Claim 1

A control system for a prime mover including channels for normal, overspeed and emergency overspeed speed control of the prime mover comprising: a plurality of "n" identical speed pick-ups receiving signals in parallel from said prime mover; a plurality of "n-1" speed translators each receiving a separate speed signal from a respective speed pick-up and each speed translator providing a proportional speed output, a primary overspeed output and a loss of signal output; an additional speed translator receiving a separate speed signal from its respective speed pick-up and providing an emergency overspeed output and a loss of signal output; a first logic circuit receiving all of said loss of signal outputs to provide a single loss of signal trip signal when said logic requirements are met; a second logic circuit receiving all of said primary overspeed outputs to provide a single primary overspeed trip signal where said logic requirements are met; a gating logic connected to said proportional speed outputs and providing a single proportional speed output and means converting said speed output into a valve position signal; and, at least one primary trip relay connected to said first and second logic outputs; and, at least one emergency trip relay connected to said emergency overspeed.