Abstract: A sine wave generator which utilizes a PROM for storing a predetermined bit pattern which is converted to a corresponding pulse waveform generated in response to a very accurate and stable clock pulse. The pulse waveform is shifted to a very exacting voltage level and is filtered by a band-pass filter to derive the desired fundamental frequency sine wave. The amplitude and frequency stable sine wave may be utilized in linear variable differential transformer (LVDT) apparatus for measuring the position of a controlled object such as a turbine valve. The arrangement may also be utilized for generating additional sine waves bearing some predetermined phase relationship with respect to one another for other control or signal processing applications.

Abstract: Hydraulically operated turbine steam admission valves wherein each valve has its own microcomputer control. In the event the valve gets stuck due to possible contamination in the hydraulic system, the microcomputer control provides an oscillatory control signal to dither the valve. If the valve remains stuck after dithering action it is provided with a control signal of an initial magnitude greater than that normally required to close the valve.

Abstract: A serial data communications network in which a plurality of stations communicate among one another in an orderly and collision-free manner on a single serial bus. Each station incorporates an improved bus access circuit to operate in cooperation with the bus access circuit of every other station in the network. The resulting effect as to each station is the assignment of a unique, recurring time window during which the station may initiate a transmission on the serial bus exclusive of all other stations.

Abstract: A turbine control system which includes dual controllers having microcomputer processing circuits and capable of transmitting and receiving digital information to and from a plurality of valve position control circuits, also including their own microcomputer circuitry for controlling turbine steam admission valves. An operator's panel provides for two levels of automatic control as well as a manual backup which is communicative directly with all of the valve position control circuits. Overspeed protection control as well as fast valving is provided by redundant speed control circuits.

Abstract: A method is described for electrically converting an analog signal into a digital representation in a manner that maximizes noise rejection. The digital representation is formed from a preselected number of discrete points corresponding to sampled approximations of the analog signal. In establishing the magnitudes of the respective points, digital samples of the analog signal are taken at a predetermined number of discrete coordinates along the analog signal on either side of the respective discrete points. The predetermined number of coordinates are averaged and employed as corresponding approximations for the respective discrete points in the digital representative reproduction of the analog signal. The effects of harmonics of power line frequencies associated with processing electrical equipment are minimized by sampling the discrete coordinates for a particular point over an integral number of cycles of the power line frequency.

Abstract: A method is described for electrically converting an analog signal into a digital representation in a manner that maximizes noise rejection. The digital representation is formed from a preselected number of discrete points corresponding to sampled approximations of the analog signal. In establishing the magnitudes of the respective points, digital samples of the analog signal are taken at a predetermined number of discrete coordinates along the analog signal on either side of the respective discrete points. The predetermined number of coordinates are averaged and employed as corresponding approximations for the respective discrete points in the digital representative reproduction of the analog signal. The effects of harmonics of power line frequencies associated with processing electrical equipment are minimized by sampling the discrete coordinates for a particular point over an integral number of cycles of the power line frequency.

Abstract: A low-cost, single-point analog subsystem comprising a pre-amplifier signal conditioner, a dual-slope integration analog-to-digital converter, and a computer interface circuit. The unit is capable of rejecting high common mode voltages while maintaining extremely high system accuracies. The main application for the invention is in interfacing transducer or instrumentation analog data with a digital computer. The interface circuitry allows the computer to select its channel in an asynchronous manner through special controllogic and without the necessity for employing conventional multiplexing equipment.

Abstract: A microprocessor-based turbine speed controller which incorporates a set of permanently programmable memory devices for characterizing the control of turbine speed in real time is disclosed. A speed monitoring interface circuit included in the speed controller is governed by the microprocessor in accordance with the processing of one program stored in one or more of the permanently programmable memory devices to generate speed measurement data words representative of actual turbine speed. In addition, a power-on initialization circuit initializes the microprocessor at the time of power turn-on to process another program stored in one or more of the permanently programmable memory devices for initializing a plurality of predetermined registers contained in the speed controller corresponding to the characterized speed control operation to be performed by each. Further apparatus and programmed instructions for the control thereof are employed to detect a malfunction in program execution by the microprocessor.

Abstract: A metering system for electric utility power line measurements includes voltage and current signal inputs that are randomly sampled and converted to binary representations. A system sequence controller and calculator provides programmed control for processing digital control and data signals and for producing digital calculations of electric energy parameters from the binary representations of the instantaneous signal values. Memory registers totalize and accumulate digitally calculated values for producing visual displays and output signals that correspond to electric energy parameters to be measured.

Abstract: In an analog data acquisition system, used for digital treatment, analog signals of different levels received from remote locations are amplified with a selected gain before being converted by a common A/D converter. A discretely variable gain amplifier is used in which a series of programmed predetermined ranges are sequentially tested against the capability of the A/D converter in relation to the particular input analog signal. The first acceptable gain is selected and a code can be used to identify the selected gain for digital treatment of the derived corresponding digital signal.

Abstract: Low level analog signals from remote locations are amplified after being converted into two consecutive analog signals of opposite polarities and a digital system causes A/D conversion to occur in two successive readings corresponding to said polarities and an algebraic combination of the two successive readings in binary form provides a true reading which is made available for digital processing by a special control circuit.