Abstract: A steam pressure rate limiter for a steam turbine system reduces the setting of a steam control valve when a rate of decrease in steam pressure is detected which exceeds a threshold value of rate of decrease. A floor on control of the steam control valve is enforced in order to maintain a predetermined amount of steam flow to the turbine thereby to provide for cooling of the turbine.

Abstract: An overspeed detection circuit for producing an overspeed trip signal for shutting off a supply of motive fluid to a prime mover upon the prime mover exceeding an overspeed trip limit includes a differentiating circuit effective to differentiate a speed signal to produce an acceleration signal related to the rate of change in the speed signal. The acceleration signal is summed with the speed signal to produce an effective speed signal which anticipates the crossing of an overspeed threshold when a fault permits a constant speed increase to occur but does not force the summed signal to cross the overspeed threshold when normal speed control is exercised.

Abstract: A control system for a prime mover may include a proportional speed control, a primary overspeed control and an emergency overspeed control. The proportional speed signal is obtained from select highest value logic, whereas overspeed and loss of speed signals are submitted to two out of three logic and two out of four logic, respectively. A passive emergency overspeed channel is provided in combination with the primary overspeed channel to respective de-energize and energize trip relays connected to electrohydraulic trip devices.

Abstract: This disclosure relates to apparatus for steam generation or boilers and more specifically, discloses a system for controlling the fluid level in a boiler drum. Drum level control requires an observation of the fluid level in the drum and also takes into account steam flow out of the drum and feedwater flow into the drum. The present invention improves upon the prior art by providing an unusually responsive drum level controller in combination with inputs relating to steam flow and water flow. This is accomplished by considering the derivative of steam flow minus water flow in combination with a fast drum level controller.

Abstract: A control system for a marine turbine power plant is disclosed wherein the input signal to an electrohydraulic valve positioning circuit for ahead and astern turbines may be directly related to a desired valve position signal input set at a throttle lever. Hence, primary control is by a desired valve position signal. A speed feedback circuit is included and selectively applied to the desired valve position signal as a valve position trimming signal. Another input into the primary control or desired valve position is a malfunction proportional control signal which tracks boiler operation, shaft vibration and overspeed. The valve position signal is applied to the valve positioning circuit through a rate limiter which may be set at a fast, normal, or slow rate depending upon an input from a system interface board.