Voltage Measurement Method Research Articles

A novel method for simultaneous measurement of current and voltage using one low-birefringence fiber

A novel method for simultaneous measurement of current and voltage employing a single monomode low-birefringence (Lo-Bi) fiber is described. This uses the Faraday effect for detection of current and the Kerr effect for detection of voltage. The waveform of the output light intensity due to the Kerr effect has been detected and the Kerr constant was measured as 5.4×10 −16 m/V −2 at 25°C. Theoretical analysis shows that the current component can be measured free from the influence of the voltage component and the two components can be easily separated.

A measurement and testing method for lubrication regimes in gear transmissions

AbstractThis paper describes the measurement and test results on oil film thickness conducted with a self‐contained gear testing machine, with pandimensional power flow, using an improved method of discharge voltage measurement. A series of experiments were conducted in an attempt to measure and analyse the lubrication regimes of involute and double circular arc gear with different lubricants under various working conditions. A formula is provided for calculating oil film discharge voltage following the recorded output of a level recorder.Experimental results show that such an improved method for discharge voltage is suitable for measurement of film thickness, and that the results are in keeping with the minimum film thickness formula for a double circular arc gear deduced by the authors. The relations between film voltage and the gear parameters of load, rotation speed, lubricant and oil temperature, are also discussed. It is asserted that such a test system has more reliable performance and is more suitable for measuring and analysing the lubrication regimes of gear transmissions than are ordinary experimental systems.

On the temperature variation of threshold voltage of GaAs MESFETs

The authors have investigated the temperature dependence of the threshold voltage of depletion-mode GaAs MESFETs with epitaxially grown n channels. An approach to threshold shift analysis that allows direct comparison with threshold measurement is taken. The contributions from various temperature-dependent effects to the threshold-voltage shift were studied, including the built-in voltage of the Schottky barrier, deep-level transients, capping layer effects, the substrate-channel built-in voltage, and the k factor which is related to channel mobility. A quasi-DC method for threshold voltage measurement, which enables threshold voltage to be measured as a function of temperature with minimum deep-level transient effect is reported. A method has also been developed to measure the temperature dependence of built-in voltage which is completely free from transient effects. The results show that the major contributors to the temperature variation of threshold voltage are the temperature dependence of the Schottky barrier built-in voltage and the effect of the capping layer.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A simplified method of electron microscope voltage measurement

A simple, rapid procedure for the determination of the accelerating voltage of a transmission electron microscope is described, which involves the measurement of the ratio of two easily found distances in the Kikuchi pattern near the [111] zone of a silicon crystal. Using enlarged prints the accuracy of voltage determination is around 0.2%, and in good conditions, direct viewing of the flourescent screen gives an accuracy of better than 1%. Data are given for 5% variation from nominal voltages of 100, 120, and 200 kV.

Electric measurement of impurity concentration in p-type epitaxially grown and ion-implanted base regions

A new destruction free method of evaluation of the impurity densities in the base region of a p-epitaxial transistor based on the Gummel-Poon model of the bipolar transistor is presented. An Early voltage measurement method is used to determine the impurity densities at the edges of the base region and the Gummel number of the base from the change of the Gummel charge Q b . The feasibility of our method is demonstrated by experimental results which are also used to determine the error ranges of the method which are within ±20%. The method is very easy to apply because it only used d.c. current and voltage measurements.

Audiometrie Bone Conduction

Audiometric bone conduction test data are obtained with a unit that permits comparison with a recognized standard because the unit can be calibrated to operate within specified limits. Proper calibration of the unit is necessary if the equipment is to be accurate. Two procedures can be helpful in determining the need for calibration: the average loss method and the input voltage measurement method. Neither should supplant calibration, but each offers a means of checking the output of the unit. Confidence in auditory test data is increased when there is a high degree of consistency among the various tests; the availability of several different tests in the audiometric series can be used to an advantage then in a determination of consistency. An additional opportunity to ascertain the existence of consistency is present when tuning fork tests are employed as part of the total evaluation. The use of a masking stimulus in the nontest ear simultaneously with the presentation of the test tone to the test ear can be extremely useful in defining the type as well as the extent of the hearing loss. Presentation of the test tone and the masking stimulus in controlled discrete steps is the key to the interpretation of masking results.

Improved voltage measurement system using the scanning electron microscope

A method of voltage measurement in the scanning electron microscope (SEM) uses a hemispherical retarding field electron energy analyzer and a feedback control loop. This paper describes improvements made both to the analyzer and the control loop to overcome some of the disadvantages of this system. A compensation technique allows for changes in the incident beam current, and this also reduces the signal caused by specimen topography. Some changes are made to the analyzer geometry which improve the spherical field symmetry of the system, and allow semiconductor devices on circular headers to be examined. The present system is now capable of measuring voltages between 50 mV and 30 V in the presence of beam current fluctuations by a factor of 3 either way. A large loop gain of 100 can now be maintained without difficulty during the voltage measurement line scans across the surface of semiconductor devices, and this ensures lower error in the measurement.

Discussion on “Method for simultaneous measurement of current and voltage on high-voltage lines using optical techniques”

Discussion on “Method for simultaneous measurement of current and voltage on high-voltage lines using optical techniques”

Method for simultaneous measurement of current and voltage on high-voltage lines using optical techniques

A laboratory device for the simultaneous measurement of current and voltage on a high voltage busbar has been constructed. A laser beam may be directed upwards from the ground to interrogate a passive optical transducer attached to a high-voltage busbar. Real and reactive power indications can also be obtained from the output, thus providing complete simultaneous information on the line state. The device uses a combination of magneto-optic and electrogyration effects in crystalline α-quartz. The latter effect has only recently been discovered and should lead to a device with small temperature dependence. The measurement transducer operates in a differential mode and the light beam passes through the quartz at a chosen angle to the optic axis. Quartz is a rugged material, very suitable for use in a transducer. A more highly developed version of the device should provide a convenient, portable, large bandwidth, research tool for diagnostic use. Eventual development could lead to an acceptable instrument for long-term operational use on the power system. Such an instrument would offer the advantages of considerably improved performance over conventional devices, at much lower cost.

Absolute Measurement of Voltage by an Electrostatic Energy-Changing Method

A new method for an absolute measurement of voltage is given. It is based on the phenomenon that, when one electrode of a capacitor supplied with a constant voltage is moved, the amount of the change of the electrostatic energy stored in the capacitor is equal to the work required for this movement. A prototype of an apparatus to be used in this method was prepared and its performance has been examined. In an ideal case, it is considered possible to determine the voltage with an accuracy of a few parts in a million with this apparatus.

High-Impulse Current and Voltage Measurement

This paper is a survey of methods of high-impulse current and voltage measurement. Typically, such measurement techniques must now include capabilities for measuring high-energy impulses having peak powers as high as many megawatts, currents as high as many mega-amperes, or voltages as high as several megavolts, with rise times as short as a fraction of a microsecond (even as short as the subnanosecond range for moderately high-energy impulses). These capabilities had to be attained in recent years to meet the needs of various areas of scientific research employing such high-energy impulses. This represents a significant extension in the state of the art of such measurement techniques beyond their more traditional role in development and testing of high-voltage bulk power system equipment. The three most commonly used methods of high-impulse current measurement are the magnetic probe, current transformer, and "pure" resistive shunt methods. These methods are treated in considerable detail. High-voltage capacitive dividers, resistive dividers, and reflection-type attenuators are covered as the principal methods of high-impulse voltage measurement, with some added discussion of the means of insulating such devices. A brief description is given of schemes involving use of laser light sources to measure high-impulse currents and voltages by means of magnetooptic and electrooptic effects. Diagnosis of the complete properties of high-power pulses is also discussed. The emphasis throughout the paper is on a review directed toward practical measurement considerations and techniques.

Display of current/voltage relationships in power-transistor circuits operating at v.h.f.

A method for the simultaneous measurement of voltage and current in v.h.f. microstrip circuits, and its application to the display of instantaneous I/V relationships in transistor power amplifiers, is described. The current waveform is obtained by integration of the voltage induced in a stripline coupling loop. Frequency response data are given, together with I/V characteristics for a 175 MHz transmitter output stage under various matching conditions.

The calibration of the sphere spark-gap for voltage measurement up to one million volts (effective) at 50 cycles

Since the issue of B.S.S. 358 in 1929 on the “Measurement of Voltage with Sphere-Gaps,” a number of calibrations of the sphere spark-gap have been put forward in Germany and the United States, but these differ appreciably amongst themselves and, moreover, are usually restricted to voltages of the order of 500 kV(eff.) and to spheres of 75 cm. diameter or less.The present paper is still another contribution to the literature on the subject, its justification being that it contains calibrations for larger spheres and at higher voltages than have hitherto been obtainable in this country.After a brief review of existing information the calibration at 50 cycles (a.c.) of a range of sphere spark-gaps is discussed in detail; methods of absolute measurement of high voltages are described, and calibrations are put forward for spheres up to 200 cm. diameter at voltages up to 1 million volts (effective) with one sphere earthed. These calibrations are based on a method of voltage measurement which is believed to be unique.Some attention has been directed towards the determination of the polarity of the high-voltage electrode when breakdown occurs, in view of the obvious importance of this feature in its relation to the breakdown of asymmetrical gaps under direct and impulsive voltages. A new type of polarity indicator is described.A correlation was observed between the noise of the spark and the polarity of the high-voltage electrode at breakdown.The effect of irradiation of the gap with radium and by other means is described.

The Measurement of High-Surge Voltages

With the application of surge tests to high voltage electrical apparatus, the question of the measurement of high-surge voltages has become a subject of prime importance. It is accordingly desired in Part I to show the practical work done in the laboratory at Sharon to calibrate the measuring devices, and in Part II to study the more interesting fundamental relationships that affect the operation and accuracy of these measuring devices. The methods of voltage measurement used are the resistance potentiometer, capacity potentiometer, and sphere gap. The potentiometers serve as dividers of the high-surge voltages for measurement at the cathode-ray oscillograph. The resistance potentiometer is a fundamental standard but requires consideration of its limitations for very rapid phenomena. In cases where these can be compensated for or are negligible, the resistance potentiometer method is very desirable. The capacity potentiometer is a secondary standard which can be calibrated. If corona and oscillations can be eliminated, it is a very desirable method of measurement, inasmuch as it is less subject to distorting the wave shape of the surge. The sphere gap is useful as a secondary standard for occasional check measurements, and it is of interest that formulas derived from smaller gaps still hold, as indicated by the check between the calculated curve for the 200-cm sphere gap and the calibration points with the resistance potentiometer.