Showing papers on "Voltage published in 1977"

Relating Epicardial to Body Surface Potential Distributions by Means of Transfer Coefficients Based on Geometry Measurements

Abstract: Although it has been known throughout this century that a complex sequence of electrical events is produced on the body surface by the electrophysiological properties of the heart, the question of how well these body surface events can be explained mathematically on the basis of experimental measurements of cardiac geometry and electrical activity remains unanswered. Recent advances in experimental capabilities have made possible the near simultaneous measurement of both cardiac epicardial and corresponding body surface potential distributions from in vivo animal preparations using chronically implanted electrodes to keep the volume conductor intact. This report provides a method for finding transfer coefficients that relate the epicardial and body surface potential distributions to each other. The method is based on knowing the geometric location of each electrode, and on having enough electrodes to establish the geometric shape and the potential distribution of closed epicardial and body surfaces. However, the method does not require that either the heart or body surfaces have any special shape, such as that of a sphere, or that any electrical quantities, such as voltage gradients, be known in addition to the potentials. The use of potential distributions to represent heart electrical activity is advantageous since such distributions can be directly measured experimentally, without a transformation to any other form, such as multiple current-generating dipoles, being required. This report includes a statement of the underlying integral equations, the procedure. for finding the equations' coefficients from geometry measurements, some considerations for computer algorithms, and an example.

A mathematical model for calculating electrical conditions in wire‐duct electrostatic precipitation devices

Abstract: A new method is developed which can be used to calculate electrical conditions in wire‐duct electrostatic precipitation devices. The method, based upon a numerical solution to the governing differential equations under a suitable choice of boundary conditions, accounts for the effect of space charge and is applicable over the entire range of current and voltage before sparkover. The procedure yields voltage‐current characteristics and determines the electric potential and electric field strength as functions of position for each current and applied voltage. Predictions of the theory are compared with existing experimental data and the agreement is excellent.

A simple two-dimensional model for IGFET operation in the saturation region

Abstract: A model is developed for an IGFET operating in saturation and accounting for the two-dimensional potential distribution in the section of the surface space-charge region adjacent to the drain. This section is treated as a volume obeying Gauss's law, thereby enabling the charge contained in it to be related to the integral of the electric displacement density normal to its surface without the need to consider the detailed distribution of charge inside. The resulting model shows, explicitly, the dependence of device output characteristics on applied potentials, geometric and processing parameters. It is also shown that by making adequate approximations, simple yet accurate forms of the model are obtained. The accuracy of the model is demonstrated by comparisons between calculated and measured device output characteristics.

In situ processing of organic ore bodies

Abstract: A method and apparatus for fracturing and/or heating subsurface formations wherein an alternating current electric field is produced in the frequency range between 100 kilohertz and 100 meghertz between electrodes spaced apart in the formation and a radio frequency generator supplying a voltage between said lines with suitable loading structures tuned to the frequency of the generator to resonate the electrodes as a parallel wire transmission line which is terminated in an open circuit and produces a standing wave having a voltage node at the end of the line.

Digital processing and calculating ac electric energy metering system

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.

Battery thermal runaway monitor

Abstract: A device for determining a thermal runaway condition in a nickel-cadmium tery. A current sensor develops a DC voltage proportional to battery current and a converter converts the voltage to a pulse train whose frequency is directly proportional to battery current. The pulse train frequency is monitored for fixed periods of time and changes of frequencies are used to determine the slope of the charge current. A maximum allowable slope is specified and fed into a binary up/down counter which also counts the pulse train frequency. When the difference between two pulse train frequency readings is greater than the maximum allowable, a possible thermal runaway condition is indicated and after a predetermined number of consecutive indications, an indicator is energized to provide a warning.

DC Treeing Breakdown Associated with Space Charge Formation in Polyethylene

Abstract: It is well known that space charge accumulation has a great influence on both the short-time and long-time breakdown strengths of plastic insulation systems operating under direct voltages. In this paper, dc treeing phenomena initiated from the tip of a needle electrode inserted into a polyethylene specimen have been investigated under various conions. The characteristics of four kinds of trees, dc tree, short-circuit tree, polarity reversal tree and impulse tree, were investigated as a function of the voltage-rising speed, period of dc prestress, time before the short-circuit or the application of a voltage of reversed polarity, impulse voltage, needle electrode material and temperature, etc. Also, thermally stimed current (TSC), thermoluminescence (TL) and photo-induced current techniques were applied to estimate the nature of the trapped carriers and carrier trapping centers. From the experimental results, it was concluded that a homo-charge is formed at high electric stresses and that the homo-charge induces an electric field distortion around the needle tip. In order to explain the length of the tree as a function of the various factors mentioned above, a model for the space charge formation is proposed, including the process such as charge injection, trapping and its diffusion.

Weighted capacitor analog/digital converting apparatus and method

Abstract: An array of binary weighed capacitors, an additional capacitor having a capacitance value equivalent to that of the least of the binary weighted capacitors, a voltage comparator, switches for interconnecting the capacitors with certain predetermined voltage levels and the comparator, and a sequencing circuit are included. One side of all of the capacitors is connected to one input terminal on the comparator and the other side has applied thereto the signal to be quantized. Switch sequencing combines divided portions of a reference voltage with the signal to be quantized for presentation to the input of the comparator which thereby provides a serial digit output connected to the sequencing circuit. In this fashion, a linear conversion between an analog and a digital signal is made by the sequencing circuit. A nonlinear converter between digital and analog signal presentation is also disclosed.

Alternating-current fed power supply

Abstract: An A.C. voltage fed power supply for D.C. gas-discharge lamps is disclosed having full-wave rectifying means connected on the A.C. side to at least two phase-adjusting networks for forming mutually phase-shifted partial currents and connected together on the D.C. side to superimpose the rectified, phase-shifted partial currents. Each phase-adjusting network is connected through the full-wave rectifying means to the same load impedance at the two D.C. voltage output terminals.

Currents induced in the human body by high voltage transmission line electric fieldߞMeasurement and calculation of distribution and dose

Abstract: Electric field measurement provides a basis for calculating the induced human body currents. Distributed body current calculation procedures are presented for an erect human on the ground and on a tower leg in a working position. An electric field dosimeter measurement provided a basis for calculating the time integral of induced body currents. Practical measurements show a much lower electric field exposure than that calculated on the basis of the maximum field in a work area. This work also enables researchers to relate biological research to practical electric field induced currents in humans.

Pulse-charging type electric dust collecting apparatus

Abstract: An improved pulse-charging type electric dust collecting apparatus is described herein, which comprises dust collecting electrodes and high corona-starting-voltage discharge electrodes disposed in opposed relationship to the dust collecting electrodes, both electrodes being arranged within a main body casing having a gas inlet, gas outlet and a dust exhaust port. An adjustable D.C. high voltage power source establishes a principal electric field between the electrodes, and an adjustable varying voltage power source having an adjustable magnitude, waveform width and repetition period is connected in series to the adjustable D.C. high voltage power source. After having intensely charged dust particles floating in a dust-containing gas introduced between the respective electrodes through the gas inlet by bombardment with the ion current under the high principal electric field, the dust particles are subjected to strong Coulomb's forces to be effectively adhered onto the dust collecting electrodes. Collected dust is exhausted to the exterior, while cleaned gas is discharged through the gas outlet. By adjusting the average value of the ion current independently of the principal electric field to inhibit inverse ionization by controlling the magnitude, waveform width and repetition period of the adjustable varying voltage, dust can be efficiently collected without inverse ionization even when it has an extremely high resistance.

Optical methods of electrical measurement at high voltage levels

Abstract: Optical methods to measure electric parameters and transmit the information from high voltage circuits to ground potential are described and evaluated in the light of the specific requirements of high-voltage measurement applications. The history and physics of a variety of optoelectrical methods found suitable for electrical measurement applications are introduced. Existing optical devices for measuring alternating, direct, and impulse currents and voltages in high-voltage circuits are reviewed with emphasis on the operation and features of several selected methods. The use of these techniques in industrial systems, in research laboratory apparatus, and in reference standards laboratories is discussed.

Voltage Measurements within the Nonequilibrium Region near Phase-Slip Centers

Abstract: We have used complementary sets of normal and superconducting probes to study the nonequilibrium region near phase-slip centers in narrow superconducting strips. An exponentially decaying branch imbalance potential, ${\ensuremath{\mu}}_{Q}$, is observed and the decay length, the quasiparticle diffusion length, is measured directly and compared to the phase-slip resistance.

Timing signal generator circuit

Abstract: A timing signal generator includes a field-effect transistor having a drain supplied with a command signal and a source connected to an output node. The gate of the transistor is connected to a circuit node which is precharged to a voltage to render the transistor conductive prior to the activation of the command signal. A delay circuit having a predetermined delay time has an input connected to the output node and an output connected to a circuit for discharging the output node and the circuit node in response to the output of the delay circuit.

Energy management system

Abstract: The present invention relates to an energy management system comprising an energy storage, a control system and a power converter supplying power to a load. The energy storage is arranged in individual energy units and the power converter is provided with a switching system for controlling the voltage over the load. The switching system comprises multiple parallel-connected power switches and at least one of the power switches is connected to each energy unit. The control system comprises individual control units, each being configured to monitor the status of a dedicated energy unit and produce an individual enable signal indicative of the status. Each power switch is configured to be controlled by the individual enable signal and a first control signal, wherein the control system is configured to connect multiple energy units in parallel to the load.

Junction termination extension (JTE), A new technique for increasing avalanche breakdown voltage and controlling surface electric fields in P-N junctions

Abstract: Extremely high breakdown voltages with very low leakage current have been achieved in plane and planar p-n junctions using an ion implanted junction extension for precise control of the depletion region charge in the junction termination. Theory is presented which shows a greatly improved control of both the peak surface and bulk electric fields in reverse biased p-n junctions. Experimental results show breakdown voltages better than 95% of the ideal and at lower leakage current than the corresponding unimplanted devices. For example, diodes with a normal breakdown voltage of 1050 volts with a .5ma leakage current become 1400 volt (1450 ideal) devices with a 5µa leakage current. Applications of the technique are feasible in MOS technology, as would be expected, but are even more attractive in power devices in which the dramatically reduced surface fields are just as important as the extremely high breakdown voltages since it means more flexibility in passivation techniques, two of which we have used to date. Our results have also shown that the implant can be at a variety of temperatures with a good degree of success, extra process flexibility being the goal of these tests.

Display system for facilitating the setup of a tuning system

Abstract: In a tuning system for a television receiver including a memory for storing binary signals representing tuning voltages corresponding to various channels a viewer may select, during a tuning voltage setup mode in which the binary signals representing the tuning voltages are generated in response to viewer control, a multiplexer couples predetermined selected ones of the binary signals representing the tuning voltages to a digital channel number display unit to provide a viewer with an indication of the relative tuning position. The multiplexer also couples binary signals representing the letter "A" to the channel number display during the tuning voltage setup mode to distinguish the tuning voltage setup mode from other modes of operation of the tuning system. In addition, during a channel selection setup mode, in which a viewer selects the channels he does not wish skipped during normal operation of the tuning system, the multiplexer couples binary signals representing the letters "CH" to the channel number display to distinguish the channel selection tuning mode from the tuning voltage setup mode and the normal operating mode.

Digital clock recovery circuit

Abstract: A digital clock signal tracks a pulse stream data signal by developing two phase-lock restorative voltages through a phase-locked loop circuit which control the loop VCO that generates the clock signal, one voltage, designated as fine, being developed through a digital up/down counter and a digital/analog converter whenever the phase difference between the two signals exceeds a first threshold, and the second voltage, designated as coarse being generated by combining with the fine voltage a voltage to reduce or increase its value before application to the VCO so that the altered control voltage rapidly restores phase-lock whenever the phase difference exceeds a second threshold greater than that of the first.

High efficiency DC to DC converter

Abstract: A DC to DC converter has an unregulated input and provides a pair of regulated outputs which independently provide variable power on demand to two independent loads at a substantially constant output voltage. The converter includes three major sections, the input oscillator and pulse width modulation section, the isolated negative DC regulator and the isolated positive DC regulator. Each of the DC regulators is current limited and each is provided with overvoltage protection. One of the output regulators provides improved efficiency through the use of a pair of appropriately connected catch diodes which decrease current change through a filtering inductor, and through implementation of a combined regulator preload resistor and AC pulse width modulating switching transistor drive current source. The converter is a compact modular unit having a low profile with circuit components arranged to minimize temperature instability.

Voltage-controlled type oscillator

Abstract: A voltage-controlled type oscillator includes a differential amplifier constituted by a first and second transistors for establishing a current, as the collector current of the second transistor, proportional to an input control voltage, and an oscillating device for producing an oscillatory signal whose frequency is determined by that current. An element having a p-n junction is connected between the second transistor and the oscillating device and a further transistor is connected between the first transistor and a power source. A portion of the current flowing from the oscillating device is divided as a base current to the abovementioned further transistor whereby an adverse influence by the base current of the second transistor is eliminated. Thus the oscillation frequency is accurately proportional to the input control voltage.

Ground fault circuit interrupter

Abstract: A device for sensing current flow in an electric conductor employs a ferromagnetic core coupled to the conductor and a control winding on the core for applying a periodic magnetic flux to a part of the core of a magnitude to vary the core permeability, preferably driving a part of the core in and out of saturation. The periodic flux interrupts any flux circulating in the core due to current flow in the conductor. An output winding on the core has a signal voltage induced therein whose amplitude is determined by the rate of change of the interrupted circulating flux. The device effectively amplifies a small current input signal to a relatively high output level. A bias winding may be wound on the core to compensate for stray magnetic fields in the vicinity of the device.

Tree Initiation in Polyethylene by Application of DC and Impulse Voltage

Abstract: The results of tree-initiation tests using impulse voltages show that the time required for the build-up of space charge at 25C is 30?s~80?s. The results of prestressing tests with DC and superimposing impulse voltages show that the space charges are homo-charges. An investigation of tree-initiation in polyethylene was carried out using dc and impulse voltages, the latter having a wave-front duration ranging from 1 ?s to 700 ps. The relationship between the tree-initiation voltage and the duration of the wave-front of the impulse voltage shows that the times required for the build-up oif the space charge at the tip of a needle electrode are 30?s~140?s at 40C for both polarities and greater than 700 ?s for the positive needle and 80?s~l40?s for the negative needle, respectively at 60C. The tree i Ltiation voltage decreases when the impulse voltage is superimposed on a dc voltage of the opposite polarity and increases when the impulse voltage and the dc voltage are of the same polarity. Some of the samples were prestressed with dc voltage for 10 minutes, and were then subsequently tested by applying an impulse voltage with a wavefront duration of 1 ?s after a waiting period of 2, 30 and 60 minutes, respectively. The tree-initiation voltage was reduced in a similar manner as when an impulse was superimposed on a dc voltage of opposite polarity.

System for determining the current-voltage characteristics of a photovoltaic array

Abstract: A nonlinear load circuit, consisting of a transistor and a resistor in series, is provided for the photovoltaic array under test. Base bias for the transistor is supplied via the source-to-drain path of a field effect transistor (FET). A ramp signal is fed to the gate of the FET. As a result of the nonlinear relationship between the gate voltage and source-to-drain current of the FET, equal ramp steps result in a nonlinear effective load for the array under test. This produces a very gradual change in load impedance for each ramp step in the regions of high current output from the array ("current mode"), and relatively greater changes in load impedance for each ramp step at output levels of lower current and higher voltage from the array ("voltage mode"). Advantageously, the array is illuminated by a pulsed flash lamp. A photosensor detects the light level incident on the array, and comparison circuitry provides a "sample" pulse each time that the incident light level is at a selected value. This "sample" pulse gates a pair of sample and hold circuits that respectively sample the array output current and voltage under the load condition determined by the present ramp step. Consecutive like operations facilitate measurement and plotting of the complete current-voltage curve.

Ink jet device

Abstract: PROBLEM TO BE SOLVED: To provide an ink jet device capable of solving in a simple structure a problem of accumulation of a residual electric charge on a protection layer and of achieving stable ejection. SOLUTION: A voltage applying means 8 for applying, across a diaphragm 11 and a substrate layer 25 of an individual electrode substrate 2, a voltage of which the pole is different from that of a voltage to be applied across the diaphragm 11 and an individual electrode 21 by a driving means 7. In terms of the voltage applying means 8, the voltage of the individual electrode 21 in a condition that a switch array in the driving means 7 is in an ON state is determined by a driving signal. When the switch array is in an OFF state, the individual electrode 21 becomes a floating condition (a high impedance condition) and the individual electrode 21 has a voltage which is obtained such that the voltage of the voltage applying means 8 is divided by a capacity between the individual electrode 21 and the diaphragm 11 and a capacity between the individual electrode 21 and the substrate layer 25. As the poles of the driving means 7 and the voltage applying means 8 are different from each other, a reverse electric field is applied to the individual electrode 21 and the diaphragm 11 so that it is possible to suppress the accumulation of the residual electric charge. It is not necessary to directly apply a voltage having a reverse pole to the individual electrode 21, thereby simplifying the structure.

Optical methods for measurement of voltage and current on power systems

Abstract: The basic principles of optical methods for measuring voltage and current at high voltage are presented. These include the magneto-optic effect, the electro-optic effect and the electrogyration effect, plus various detection and noise reduction techniques. Both free path and enclosed path devices which have been constructed on these principles are described. The viability of these devices for the electricity supply industry is assessed.

Finite element solution of complex potential electric fields

Abstract: A computer program is described, which calculates electric fields in configurations with both capacitive and resistive distribution of potentials. Resistive coating on the surface of the insulation as well as conductivity in the insulation itself can be handled.

Device for determining the charge condition for a secondary electric storage battery

Abstract: A device for determining the charge condition of a secondary electric storage battery, and including a digital integrator comprising a pulse generator for producing pulses at a frequency proportional to the magnitude of the instantaneous battery current, and an up-down counter for counting the pulses in a sense (i.e. up or down) dependent upon the battery current direction. A switching arrangement operates to couple selectively the pulse generator or an adjustment pulse generator to the counter, and a comparator controls the supply of pulses to, and the sense of counting in the counter, when the adjustment pulse generator is coupled thereto in accordance with the result of a comparison of the counter setting and of a function signal. A function generator, programmable in accord with the relationship between temperature, no-load voltage, and charge condition of the battery concerned, is controllable in accord with the instantaneous temperature and no load voltage of the battery so as to generate the function signal to represent the associated charge condition.

Digital fault-location calculation system

Abstract: Provided is a digital fault-location calculation system which comprises first means for obtaining data including voltage and current information of a power transmission system subjected to fault-location calculation, a computer, and second means coupled between the first means and the computer for transferring the obtained data to the computer from the first means. The computer has at least two functions, one of which is the detection of occurrence of a faultin the transmission line and the other is the calculation of distance from the point of installation of the system to the fault point, in response to the data transferred through the second means and in accordance with predetermined processes. The distance to the fault point is computed by the other function of the computer only upon the detection of occurrence of a fault in the transmission line by the one function of the same.

Optical observation of pre-breakdown and breakdown phenomena in transformer oil

Abstract: High-speed time-resolved Schlieren photographs are taken between impulse voltage application and breakdown in transformer oil using an image convertor camera at various applied voltages and framing speeds. Needle-to-plate electrodes are used and the oil is under vacuum. The pre-breakdown disturbance accompanied by shock waves emanates from the needle electrode for both polarities of the needle point. The disturbance from the negative point propagates step by step like a lightning discharge in air, while that from the positive point moves radially and reaches the plate electrode in one step. The pre-breakdown disturbance seems to be a gaseous phase which is generated in the liquid.