High-voltage Impulse Measurements Research Articles

Design and implementation of a programmable high-voltage impulse measurement system

High-voltage impulses (HVIs) are produced under laboratory conditions in order to emulate actual internal (switching) and external (lightning, thunderbolt) voltages. HVI resistance tests are essential to meet national and international standards on the production of electromechanical devices and materials, such as switchgears, and transformers that operate under these actual conditions. Accurate measurement of HVI is excessively difficult since the voltage level is so high, while the time parameters are relatively constricted. In this study, a reliable automatic HVI measuring and recording system, which accommodates a series of hardware and software designs in order to satisfy the constraints of the standards, is devised. The system provides high performance for measurement speed, resolution, and accuracy. Its lightweight, portable, and economical design brings about a prevalence of availability for medium- and small-scale electromechanical manufacturers.

Establishment of National Standard on High Voltage Impulse Measurement

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HV Impulse Measuring Systems Analysis and Qualification by Estimation of Measurement Errors via FFT, Convolution, and IFFT

Quality of high-voltage (HV) impulse measurements requires adequate dynamic performance of measuring systems (MS) with respect to the waveforms to be measured. Qualification of MSs for various impulses is a prerequisite for repeatability and reproducibility of HV testing results. Alternative qualification procedures are considered with respect to the standard full lightning impulse including evaluation of significance of its frequency components. Duality of step responses and amplitude-frequency responses is described in detailed examples. Special attention is paid to creeping, encountered with some converting devices. Variations of MS response parameters can lead to improper conclusions when only conventional examination of the dynamic behavior is used. Evaluation of the response parameters is an unnecessary step, which brings additional errors to the HV measurements. The paper is pointing out advantages and practical achievements of the frequency-domain qualification of dynamic properties based on the step response data obtained both experimentally and analytically. Measurement errors of the impulse peak value and time parameters have been evaluated via fast Fourier transform (FFT), convolution, and inverse discrete Fourier transform (IFFT) for a commercial divider. Direct determination of the HV impulse measurement range, no need for any additional parameters, and illustrative graphical presentation of results are the main advantages of this approach. Limitations of different qualification approaches are discussed.

Assuring the quality of impulse voltage calibration results issued by a calibration laboratory

This paper describes high voltage impulse measurements made under the controlled conditions of a calibration or national measurement laboratory to establish the best agreement that could be achieved in comparison measurements on small reference dividers. This comparison to establish mutual international traceability between NRC and National Grid has shown that the peak voltage of a smooth lightning impulse was measured by both laboratories to within 0.2% with an estimated uncertainty of /spl plusmn/0.2% at a level of confidence not less than 95%. The authors make recommendations on how calibrations of reference measuring systems should be performed.

Comparative impulse voltage measurements at the national measurement laboratory (nml), csiro, australia, and the institute for national measurement standards (inms), nrc, canada

This paper describes high voltage impulse measurements made under controlled conditions in two national measurement institutes to establish the best agreement that could be achieved in comparison measurements on small reference resistor dividers. These measurements at NML and INMS show that the peak voltage of a smooth impulse (measured as the peak reading of the record times the scale factor) can be measured in each laboratory with relative agreement within 4 mV/V. The uncertainty of this relative agreement, calculated from the standard deviation of the differences in each set of measurements, is 2 mV/V at a level of confidence of 95%. The relative agreement of front times was within 15 ms/s, with an uncertainty of 4 ms/s. The relative agreement of times to half-value was within 4 ms/s with an uncertainty of 2 ms/s.

Standards for digital recorders for measurements in high-voltage impulse tests

The background to the first standards for digital recorders for high-voltage impulse measurements is reviewed briefly. The emphasis in the first issues is given and the import of the decisions made in these early documents presented. The changes in the latest revision of Institute of Electrical and Electronics Engineers (IEEE) Std. 1122-1998 are reviewed briefly and contrasted with the approach in the latest Committee Draft for Voting on the revision of International Electrotechnical Commission (IEC) Document 1083-1. The importance of the changes in these documents is discussed. New work in the field is summarized and recent developments in digital recorders are discussed. The present status of digital measurements is summarized and proposals for future improvements to the standards are put forward.

Precision digital filters for high voltage impulse measurement systems

This paper reports the design, testing and practical applications of two types of high order FIR digital filters for noise reduction and data smoothing of high voltage impulse waveforms. Particular attention is paid to the estimation of the error limits introduced by the digital filters. The error estimation involves the analysis of the frequency components of the impulse waveforms, the ripple calculation of the filters and testing of the filters with simulated and real impulse waveforms. The relationships between the filter parameters and the required filter accuracies are established.

Comparative High Voltage Impulse Measurement.

A facility has been developed for the determination of the ratio of pulse high voltage dividers over the range from 10 kV to 300 kV using comparative techniques with Kerr electro-optic voltage measurement systems and reference resistive voltage dividers. Pulse voltage ratios of test dividers can be determined with relative expanded uncertainties of 0.4 % (coverage factor k = 2 and thus a two standard deviation estimate) or less using the complementary resistive divider/Kerr cell reference systems. This paper describes the facility and specialized procedures used at NIST for the determination of test voltage divider ratios through comparative techniques. The error sources and special considerations in the construction and use of reference voltage dividers to minimize errors are discussed, and estimates of the measurement uncertainties are presented.

Qualifying an impulse digitizer for measurements in HV impulse tests

A standard is being prepared for digital recorders for measurements in HV (high-voltage) impulse tests. How the main tests described in the proposed standard can be applied toward qualifying an impulse digitizer for HV impulse measurements is discussed. Experimental results from the application of these techniques to different digitizers are presented. A major problem in using digital recorders in HV laboratories is electromagnetic interference. Previous low-frequency measurements have indicated that high frequencies can be a problem. Some measurements at high frequencies are reported. The consequences of these measurements for electromagnetic compatibility are discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The Application of Constrained Signal Reconstruction Methods in High Voltage Impulse Measurement

Two methods of signal reconstruction — the constrained iterative reconstruction method (CIR) and the constrained least squares reconstruction method (CLSR) have been used to compensate for the inadequate response of two high voltage impulse measuring systems. Both methods have been shown to produce accurate estimates. However, the CIR method is favoured as it produces stable results under all of the presented conditions.

Active network for correcting impulse-voltage measurements

High-voltage impulse measurements are usually carried out by using a divider system which may distort the impulse. The paper presents a method for the correction of the input signal from the distorted output signal by using a wide-band active network. The method is demonstrated by several test results. The accuracy analysis of the method is also carried out theoretically. The correction method is simple to apply.

Correction to "A New Approach to Minimize Response Errors in the Measurement of High Voltage Impulses"

Correction to "A New Approach to Minimize Response Errors in the Measurement of High Voltage Impulses"

A New Approach to Minimize Response Errors in the Measurement of High Voltage Impulses

A New Approach to Minimize Response Errors in the Measurement of High Voltage Impulses

A New Appproach to Minimize Response Errors in the Measurement of High Voltage Impulses

Response errors in the measurement of rapid high voltage irpulses are shown to be related to three parameters, while a fourth parameter defines the shortest event for which the relationships are valid. These parameters are used to demonstrate the theoretical and practical adjustment of dividers for minimum response errors. In this way the errors can be brought within acceptable limits.

Calibration and Checking Methods of Rapid High-Voltage Impulse Measuring Circuits

Errors in high-voltage impulse measurements are classified as scale factor errors and errors due to limitations in response characteristics. Running work within the International Electrotechnical Commission (IEC) gives tentative requirements intended to keep the mentioned errors within reasonable limits. The theoretical basis of these requirements is presented and checked against some practical cases.