Abstract: A fast opening valve apparatus includes an electronic sensing circuit to determine when a positional error signal exceeds a predetermined reference value corresponding to an opening rate reference value. The sensing circuit provides a fast open command signal which is applied to a solenoid valve which is hydraulically coupled in parallel with a control servo valve. The control servo valve hydraulically couples a primary source of hydraulic fluid under pressure to a valve actuator which is mechanically coupled to a valve stem of an associated steam valve desired to be controlled. The activated solenoid valve opens a supplemental hydraulic fluid path between the valve actuator and the primary source of hydraulic fluid. To ensure an adequate hydraulic fluid pressure at the input of the servo valve and solenoid valve, an auxiliary source of hydraulic fluid under pressure may be coupled upstream of the servo valve and solenoid valve.

Abstract: This invention provides a method and apparatus for early detection of wiping contact between a rotating shaft and bearing metal in a flow lubricated bearing. In one form of the invention, a temperature sensor is provided to monitor bearing temperature at a location on the bearing in proximity to the maximum loading position. The sensor signal is sampled periodically by a plurality of sample and hold circuits so that present and immediately past values of the bearing temperature are always on hand. The sampled values are applied to a set of subtracters, each one of which provides a signal representing the difference between two consecutively sampled temperature values. Selected ones of the temperature differences are applied to summers and the largest sum is selected by a high-value selector and compared with a preselected setpoint value representing an excessive temperature change for a given time period.

Abstract: An electrohydraulic control system and method are disclosed for operating valves controlling the admission of steam to a steam turbine. The system includes a mode transfer unit for effecting a transfer between a full arc mode of valve operation to a partial arc mode of operation such that the temperature of the steam turbine varies in a controlled manner, thus permitting control of turbine stresses. Apparatus is described for generating mode flow signals, combining the signals using time ratio switching such that during a mode transfer the signals vary linearly with an admission reference factor characteristic of each mode, and generating valve lift signals from a combined flow signal using multi-slope, piecewise linear approximations to the flow-lift characteristics of the full arc mode of valve operation. The system permits mode transfers wherein total steam flow is held substantially constant and first stage turbine temperature is caused to vary linearly with admission reference factor.