Showing papers by "Westinghouse Electric published in 1992"

Unified power-flow control concept for flexible AC transmission systems

Abstract: The author outlines the technical and economic factors which characterise the uniform, all solid-state power-flow controller approach for real-time controlled, flexible AC transmission systems. The unified power-flow controller in its general form can provide simultaneous, real-time control of all basic power system parameters (transmission voltage, impedance, and phase angle), or any combinations thereof, determining the transmitted power. The parameters selected for control can be changed without hardware alterations, e.g. the function of the controller can be changed from that of a phase-shifter to that of a series line compensator, or vice versa, with or without additional terminal voltage regulation and shunt VAr compensation, to adapt to particular short term contingencies or future system modifications. >

Plant maintenance with predictive diagnostics

Abstract: An integrated information system is provided for a plant with interactive processes running in functional equipment subsets, such as a nuclear power generation plant. Sensors are operatively coupled to monitor processes and equipment in the plant, collecting sample data for assessing operational conditions and for predicting maintenance requirements based on loading of the equipment. One or more processors access the sample data and compares present conditions to diagnostic specifications, technical specifications and historical data stored in memory and indexed to equipment subsets and functional operating groups. The processor(s) generate prioritized reports to alert users to potential operational and/or maintenance problems. In addition to the prioritized reports, the processor accesses and outputs to the users reports of the diagnostic and technical specifications applicable to the process parameters exhibiting the potential problems. These specifications are provided in successive levels of detail and are cross referenced between related processes and related items of equipment. The information system integrates operations, maintenance, engineering and management interests in a common database of information via network-coupled data terminals.

Performance Deterioration in Industrial Gas Turbines

Abstract: This paper describes the most important factors affecting the industrial gas turbine engine performance deterioration with service time and provides some approximate data on the prediction of the rate of deterioration. Recommendations are made on how to detect and monitor the performance deterioration. Preventative measures, which can be taken to avoid or retard the performance deterioration, are described in some detail.

Electronic circuit breaker with protection against sputtering arc faults and ground faults

Abstract: A circuit breaker bandwidth limits a sensed rate of change of current, di/dt, in the neutral conductor of a protected electrical system and fullwave rectifies the bandwidth limited di/dt signal for comparison with an instantaneous trip reference signal. The bandwidth is selected to provide a selected relative sensitivity of the instantaneous trip to sinusoidal currents associated with overcurrent faults and step currents associated with sputtering arc faults. The rectified bandwidth limited di/dt signal is also filtered and delayed for comparison with a delayed trip reference signal. The time constant for the filter is selected to provide a selected relative sensitivity of the delayed trip to overcurrent faults and sputtering arc faults. A low mu sensing coil used to generate the di/dt signal can also serve as the neutral current sensing coil of a dormant oscillator ground fault protection system.

Apparatus and method for dynamic voltage restoration of utility distribution networks

Abstract: A system and method is provided compensating utility distribution line transients such as voltage sags in a dynamic manner, by inserting a voltage signal in series with the distribution signal having a magnitude and phase to effectively cancel out the voltage deviation caused by a network disturbance. An energy storage device such as a storage capacitor is used to provide energy to an inverter circuit which is controlled to generate the series-inserted signal. Preferably a converter such as a chopper is utilized between the storage element and the inverter, to provide a constant dc input to the inverter. A controller generates a corrective error signal based upon the deviation between the utility supply voltage as affected by the disturbance, and the nominal ideal voltage signal, and adjusts the insertion voltage so as to optimize real power delivery to the utility distribution line.

CW measurement of HBT thermal resistance

Abstract: Measurements of the temperature dependence of beta and V/sub BE/ were made on AlGaAs-GaAs HBTs and used to determine device thermal resistance. The measurements were CW and not switched or pulsed in order to have a simpler procedure. With base doping greater than 10/sup 19/ cm/sup -3/, HBTs have negligible base-width modulation (i.e., flat I/sub C/ versus V/sub CE/ characteristics) which makes CW thermal resistance measurement especially direct and simple. >

The utility requirements for a distribution fault current limiter

Abstract: The need for a distribution current limiting device (DCLD) by the utility industry is addressed. An evaluation was made of what specifications would be acceptable and what DCLD technique would fill the utilities' needs. Using this survey and a distribution system analysis, a DCLD that could limit a 20 kA fault to 10 kA in a 15 kV circuit was shown to be the primary candidate for further development. The study showed that gate turn-off thyristors (GTOs) are the best technology available that could be developed into a practical DCLD. A recommendation was made to develop a DCLD using GTOs. >

Automotive current sensor

Abstract: A high-amperage current sensor is disclosed which is suitable for use in an automotive electrical system and which is operatively unaffected by changes in ambient temperature. The current sensor utilizes a shunt assembly having at least one low-resistance shunt element connectable in line between a source of electrical energy and a load. Circuitry preferably configured on an application specific integrated circuit measures voltage drop across the shunt element due to current flow. As a result, an output signal is produced which may be fed to external circuitry for further processing. In presently preferred embodiments, the sensor may comprise analog circuitry producing an analog output signal and/or digital circuitry producing a digital output signal.

Distributed aperture imaging and tracking system

Abstract: An imaging system utilizes a plurality of sensors capable of sensing objects within a field of view about a sight line. At least two sensors have different sight lines with the sight lines having known relative positions. Each sensor produces signals corresponding to positions of objects within a field of view over time. At least one sensor signal memory receives those signals and stores them in a manner enabling concurrent access to signals received from any selected combination of sensors. The processing unit and associated memory contain at least one program for selecting sensor signals from a sensor signal memory. Preferably motion detectors are provided for determining vibration, flexure or movement of each sensor. A normalizing means is preferably provided to adjust the sensor or make an appropriate modification of the signal received from the sensor.

A unified analysis of MMIC power amplifier stability

Abstract: The author develops the mathematical framework and techniques for predicting possible oscillations for all n modes in order to ensure MMIC monolithic microwave integrated circuit stability. Although the analysis is applicable to any number of combined devices, only the cases for n=2 and 4 are discussed. These two cases illustrate the special considerations that apply for small numbers of combined devices (n=2) and the difficulties in analyzing larger numbers of combined devices (n=4). It was shown that the stability of the amplifier for all modes (even and odd) can be checked using small signal analysis software. >

Windshear radar system with upper and lower elevation radar scans

Abstract: The present invention is an airborne radar system which scans the flight path of an aircraft with two radar scans, an upper elevation scan pointing above local level and a lower elevation scan pointing below the glide slope. The radar returns from the upper elevation scan are used to detect the core of the microburst. The core and a model of the windshear which uses the core are used to select angles and range cell candidates, in a lower elevation scan, for hazard detection processing. The candidates in the lower scan, which is pointing at the ground, are used to create a hazard map tested against a predetermined hazard threshold. A threshold violation results in a pilot alert. The hazard map includes a vertical factor determined through model coefficients in the radial outflow as a function of altitude. The invention applies the model to determine the total hazard factor along the glideslope using the vertical hazard of the model and altitude scaling of the horizontal hazard from the lower bar elevation to the glideslope of the aircraft. A colored hazard map can be displayed to the pilot allowing the pilot to select an abort direction based on the area of the highest hazard. The present invention also includes a radar scan with two pulse repetition frequencies which allows the elimination of non-correlated returns. The system also includes post detection integration with a sliding azimuth window to enhance the signal to noise ratio. The system also combines velocities within a single range gate to produce a velocity representing the windspeed at that range. To further enhance the determination of the windburst hazard an oriented and specially shaped window is used in an ordered constant false alarm rate process to remove ground clutter from the lower scan.

Circuit breaker with positive off protection

Abstract: A positive off mechanism for a circuit breaker includes a pair of positive off levers slideable in slots in the side plates and extendable into the path of the operating handle to prevent movement of the handle to the off position when the contacts are welded closed. The positive off levers are actuated by positive off links pivotally mounted to the side plates and coupled to the positive off levers by "dog bone" connections. The positive off links in turn are actuated by the toggle mechanism of the circuit breaker which collapses to open the contacts during normal circuit breaker operation, but which remains erect when the contacts are welded closed.

Modular mail processing method and control system

Abstract: A modular mail processing method and control system that includes a plurality of induction transport modules and a stacker/transport module. The system maintains a real time statistics concerning the mail flowing through the system. The modularity of the system increases its flexibility in adapting to sorting either incoming or outgoing mail. In addition, a variety of readers and printers can be employed in the system to meet the needs of a particular customer.

Cognitive simulation as a tool for cognitive task analysis.

Abstract: Cognitive simulations are runnable computer programs that represent models of human cognitive activities. We show how one cognitive simulation built as a model of some of the cognitive processes involved in dynamic fault management can be used in conjunction with small-scale empirical data on human performance to uncover the cognitive demands of a task, to identify where intention errors are likely to occur, and to point to improvements in the person-machine system. The simulation, called Cognitive Environment Simulation or CES, has been exercised on several nuclear power plant accident scenarios. Here we report one case to illustrate how a cognitive simulation tool such as CES can be used to clarify the cognitive demands of a problem-solving situation as part of a cognitive task analysis.

Automated rotor welding processes using neural networks

Abstract: Methods and apparatus for monitoring an arc welding process are disclosed. In a preferred embodiment, the present invention creates a digital representation of the arc created during welding and, using a neural network computer, determines if the arc is representative of normal or abnormal welding conditions. The neural network disclosed is trained to identify abnormal conditions and normal conditions and may be adaptively retrained to classify images that are not in the initial set of normal and abnormal images. In certain embodiments, other data, such as current, weld wire emission spectra, or shielding gas flow rate are also collected and the neural network is trained to monitor these data. Also, in certain embodiments, an audio signal is collected from the vicinity of the welding process and is used by the neural network computer to further classify the arc as normal or abnormal. The present invention is most preferably implemented in repetitive and continuous welding operations, such as those encountered in the manufacture and rebuilding of steam turbines.

Circuit breaker with protection against sputtering arc faults

Abstract: A circuit breaker includes an electronic trip device which responds to sputtering arc-type faults. Level detectors compare the current in the protected circuit to a plurality of threshold levels and timers time the intervals that the current remains above each threshold, with the threshold levels and intervals selected to generate a response envelope for a trip signal which approximates, with a selected margin, the response of the protected circuit to introduction of a selected inductive load such as the starting of a motor into the circuit. If the sensed current falls below a threshold level which was being timed, the associated timer is not cleared unless the current falls below the lowest threshold, so that if the sensed current increases above the associated thresholds timing resumes where it left off, and a trip signal wall be generated sooner than for an initial excursion above the threshold. Both analog and digital timer implementations are presented.

Effect of an axial magnetic field upon the development of the vacuum arc between opening electric contacts

Abstract: Two series of experiments are reported. In the first, a Helmholtz coil provides an independent, constant axial magnetic field B/sub ax/ in the gap between opening Bruce profile, chromium-copper (Cr-Cu) contacts. Peak arc currents up to 40 kA at 50 Hz are studied with B/sub ax/ up to 112 mT. For each peak current, a critical field B/sub crit/ is determined above which anode spots did not form. For B/sub ax/ greater than B/sub crit/, the time from contact parting to the formation of a diffuse vacuum arc is linearly dependent upon separation current, with a change in slope at 7-8 kA. In the second series, the contacts are designed to generate a self B/sub ax/ when current flows. The magnitude of this field is approximately proportional to the current waveform through the contacts, and it is always higher than the B/sub crit/ predicted for the instantaneous current. The time from contact parting to the formation of the diffuse arc is consistent with the first experimental series. >

System and method for monitoring synchronous blade vibration

Abstract: A system and method are provided for monitoring synchronous blade vibration in a turbo-machine. At least three sensors capable of detecting the arrival of each blade are arranged about the cylinder which surrounds the tips of the blades. The location of the sensors is selected to minimize the influence of errors in the data. To this end, and to simplify the installation of the sensors into the cylinder, the sensors may be non-uniformly spaced. The location of each sensor for purposes of constructing Fourier transforms is determined using the arrival times at the blades at each sensor, expressed as a fraction of a rotor revolution. The transform matrix is constructed for a predetermined discrete set of M harmonics, so that M harmonics are analyzed simultaneously, the number of harmonics which can be simultaneously analyzed is related to the number of sensors used. The blade arrival time data at each sensor, expressed as a fraction of a rotor revolution, is analyzed to determine the amplitude of the blade vibration at each of the harmonics selected for the set. The calculations are repeated for a variety of harmonic sets in order to accurately interpret the results in the event there is significant vibration at harmonics not included in the initial set.

Hybrid electronic fiber optic wavelength-multiplexed system for true time-delay steering of phased array antennas

Abstract: A hybrid electronic fiber optic true time-delay steering architecture is presented which retains the highly hardware compressive property of an earlier all-optical approach and introduces the economical advantages of electronics at every level possible without compromising overall performance. The architecture is particularly suited to large arrays where maximum advantage can be taken of the hardware compression. A detailed design based on this architecture is described for steering a linear, 16-element, L -band (0.7- to 1.4-GHz) array in transmit mode over a scan angle of ±20 deg with a delay resolution of 6 bits (0.63 deg). An analysis of the expected performance of the design is given together with progress toward the fabrication of the prototype system, which includes the first iteration electronic binary delay line subsystem and a single-segment, high-fidelity, directly modulated DFB laser diode fiber optic link. The experimental data from these modules is in agreement with the performance predicted from the analysis.

Tip clearance control apparatus for a turbo-machine blade

Abstract: An apparatus is provided for controlling rotating blade tip clearance in a turbo-machine utilizing conical tipped blades. The apparatus comprises an approximately conical blade ring mounted for axially sliding displacement in the turbo-machine cylinder. The conical blade ring encircles the tips of the rotating blades and forms a blade tip clearance therebetween. The tip clearance is controlled during operation of the turbo-machine by axially displacing the conical blade ring. Piston cylinders, actuated by pressurized fluid extracted from the turbo-machine, are used to displace the blade ring. Springs, adapted to bias the blade ring into a position of increased tip clearance, oppose the piston cylinder so that failure of the piston cylinder will not result in a loss of tip clearance. A blade tip clearance sensor transmits information on the tip clearance to a controller that automatically adjusts the blade ring axial position to continuously maintain the optimum tip clearance by regulating the pressure of the fluid supplied to the piston cylinders.

Synthetic aperture beamforming with automatic phase compensation for high frequency sonars

Abstract: The author discusses a phase compensation technique suitable for both high- and low-frequency sonars using displaced phase center receive elements to compute phase corrections directly from the acoustic scene. The phase compensation corrects ping-to-ping incoherence due to both medium and vehicle motion instabilities over the integration period of the synthetic aperture, thereby improving image quality. The phase compensation technique was evaluated using both simulated hydrophone data and acoustic test tank data at 550 kHz. General-purpose beamformers have been developed to allow side by side comparison of physical aperture and synthetic aperture images processed from the same set of hydrophone data. Performance results are presented for both simulated and acoustic test data, depicting the improvements provided by this phase compensation method. >

Field-dependent crossover in the vortex response at microwave frequencies in YBa2Cu3O7- delta films.

Abstract: We observe anomalous magnetic field dependence of the microwave vortex response of epitaxial ${\mathrm{Y}}_{1}$${\mathrm{Ba}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$ films, which we identify as a crossover from flux pinning to flux flow, occurring near a characteristic field ${\mathit{H}}^{\mathrm{*}}$(T). We show that the presence of the crossover depends only on adequate softening of the pinning potential U(T,H) (i.e., it is independent of the nature of the vortex transition). However, the data are in good agreement with a thermal activation model in which U(T,H)=A(T)./H. A separate analysis of the high-field, high-frequency superconducting transition yields a measure of the upper critical field ${\mathit{H}}_{\mathit{c}2}$.

Strengthening in MULTIPHASE (MP35N) alloy: Part I. ambient temperature deformation and recrystallization

Abstract: The microstructure and mechanical properties of the cobalt-based MP35N alloy (35 pct Co, 35 pct Ni, 20 pct Cr, and 10 pct Mo) were investigated following room-temperature deformation. It was found that the material showed marked work hardening at strains greater than about 0.15 to 0.2, which correlated with the formation of platelike structures on {111} planes. The initial yield strength of 390 MPa was increased to 1385 MPa by cold drawing 48 pct. Electron microscopy showed evidence that the platelike structures were both faulted face-centered cubic (fcc) twins and hexagonal martensite. Secondary strengthening from 1385 to 1935 MPa was achieved by annealing the cold-drawn MP35N at 650 °C for 4 hours. However, no structural change could be detected that could account for this large secondary strengthening. This failure lends indirect support to the proposal that this secondary strengthening could arise from solute partitioning between the fcc matrix and hexagonal martensite. Cold-worked MP35N resisted recrystallization up to a critical softening temperature of 1083 K (810 °C), at which the alloy lost 50 pct of its hardness during a 1-hour anneal. Nucleation occurred readily at and above this temperature. Growth of the new grains at temperatures close to the critical softening temperature appeared to be strongly inhibited by the martensite plates but not by twins. Residual dislocation densities were seen in the recrystallized grains in the vicinity of the disappearing martensite plates. It is proposed that these dislocations arise from local changes in lattice parameters arising from prior solute segregation to the martensite plates. A revision of the earlier solute partitioning model of secondary strengthening is proposed here — that the partitioning occurs locally, adjacent to the preexisting plates. During postanneal deformation, higher stresses are then required for fresh martensite plates (and twins) to be nucleated from the existing plates. Ultrafine grain sizes of only about 1 μm could be produced in MP35N by successive cycles of deformations and anneals at temperatures close to the critical softening temperature.

Spatial resolution of imaging noncollinear acousto-optic tunable filters

Abstract: The spatial resolution limit of noncollinear acousto-optic tunable filters used for imaging with incoherent light is derived based on phase-matching requirements. It is shown that the noncollinear filter can achieve near diffraction limited imaging. This conclusion was verified experimentally.

Ground fault circuit breaker with test spring/contacts directly mounted to test circuit of printed circuit board

Abstract: A ground fault circuit breaker in which both the fixed and movable contacts of the ground fault test switch are directly secured to the printed circuit board on which the ground fault detection circuit is implemented, with the movable contact also providing the spring bias for the test button.

Dual wound trip solenoid

Abstract: A multiple-pole ground fault interrupter, enclosed in an insulated housing, formed with multiple compartments, includes ground fault detection circuitry for detecting ground fault current that can be a personnel hazard. The ground fault interrupter includes a single trip solenoid assembly having multiple windings, each winding corresponding to one of the poles. The trip solenoid is mounted on a printed circuit board and electrically connected to the ground fault detection circuitry disposed thereon. The printed circuit board together with the trip solenoid assembly is disposed in a single compartment which reduces the amount of interconnection wiring between compartments, which, in turn, results in a reduced cost to manufacture the device. The use of a single trip solenoid assembly also results in the use of less components which further reduces the cost of manufacturing the device.

Lockable rotary handle operator for circuit breaker

Abstract: A rotary handle operator for a circuit breaker with a linearly movable handle has a housing which is mounted over the circuit breaker handle. A slide carrying a rack engages the circuit breaker handle and is slidable within a chamber in the housing. The rack engages a pinion gear sector mounted on a rotatable shaft which extends through a cover on the housing. A rotating handle mounted on the shaft is rotated to linearly operate the circuit breaker handle or is positioned thereby when the circuit breaker trips. The handle may be locked in the off position by inserting the shackle of a lock through an aperture in a lever arm on the rotating handle to urge a pin on a spring biased locking piece within the handle lever into an aperture in the housing cover, or the shackles of several locks may engage a slot in a shroud surrounding the rotating handle to interfere with rotation of the handle out of the off position. An interlock for the door of a cabinet in which the circuit breaker may be mounted is incorporated into the rotary door operator.