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Journal ArticleDOI

A Microprocessor Based Measuring Instrument for Rapid Testing of Transformer Core Material

TL;DR: An instrument using linear compensating networks and exploiting the processing capabilities of the popular microprocessor is developed for the measurement of core characteristics such as specific iron loss and the dynamic B-H curve.
Abstract: Precise knowledge of the characteristics of core material Is essential for the design of electromagnetic devices I Ike dynamos, I nstrument transformers and relays. Conventional measurement of the core characteristics Is a tedious process as it Involves collection of voluminous data and corrections thereto. An instrument using linear compensating networks and exploiting the processing capabilities of the popular microprocessor is developed for the measurement of core characteristics such as specific iron loss and the dynamic B-H curve. The necessary corrections are Incorporated In the software so that the end result can be straightaway used in design.
Citations
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Journal ArticleDOI
TL;DR: A new, high precision, dual-slope based conversion technique that directly provides a digital output of Ratio Error (RE) and Phase Errors (PE) of an Instrument Transformer (IT) under test is presented.

5 citations

Journal ArticleDOI
01 Nov 1999
TL;DR: In this paper, a PC-based automatic characterisation system (ACS) was developed to automatically characterise magnetic materials under square wave cyclic excitation from 1 kHz to 100 kHz.
Abstract: A PC-based automatic characterisation system (ACS) has been developed to automatically characterise magnetic materials under square wave cyclic excitation from 1 kHz to 100 kHz. A computer-controlled AC to AC converter has been developed for the excitation circuit. A digital oscilloscope gathers the required data through the 8255 interface card. The errors in the ACS have been analysed and overall repeatability is better than /spl plusmn/0.35%. The system has the advantages of ease of use, absence of long-term measuring system drifts and ready variation of high induction and high frequency test parameters. The system operates automatically and measurements on three commercial core materials are reported. Comparisons with the data of manufacturers are included.

3 citations

References
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Journal ArticleDOI
TL;DR: In this paper, a survey of the status of work in the higher induction and frequency ranges is given and recent papers on the measurement of rotational losses are reviewed, in partucular regarding the performance of those magnetic circuits most widely used in loss measurements.
Abstract: A brief survey of the status of work in the higher induction and frequency ranges is given and recent papers on the measurement of rotational losses are reviewed. The determination of the magnetic losses in alternating fields is considered, in partucular regarding the performance of those magnetic circuits most widely used in loss measurements. New and revised data contribute to the elucidation of the systematic errors of the Epstein square. The Epstein samples and plate samples, both of various materials, were used for measurements with single sheet testers, whereby the field strength was determined both from the magnetizing current by means of a precision resistor and direct, using field sensing coils. From these results conclusions for the appropriate value of the effective magnetic path length can be drawn. The electric power measurement particularly as regards digital procedures, calibration and uncertainties is briefly discussed.

40 citations

Journal ArticleDOI
TL;DR: In this paper, some new active circuits using active circuits are proposed for realization of sinusoidal flux in a ferromagnetic core during loss testing, which facilitates the loss measurements to be made from the primary side itself.
Abstract: Some new schemes using active circuits are proposed for realization of sinusoidal flux in a ferromagnetic core during loss testing. One of the suggested configurations facilitates the loss measurements to be made from the primary side itself. A few filter circuits enable the tests to be carried out on normal supply mains without the need for a calibration generator. Experimental results are reported to confirm the acceptability of the proposed schemes.

4 citations

Journal ArticleDOI
TL;DR: In this article, the authors developed a computerized control and measuring device which cooperates with all commonly used magnetization equipment such as an Epstein frame, single sheet yoke etc. The device delivers a sinusoidal voltage with programmable frequency and amplitude which is used to control a power amplifier supplying the magnetizing current.
Abstract: In order to investigate the magnetic properties of soft magnetic materials, especially of electrical steel sheet, with high accuracy and minimal manual operation, we have developed a computerized control and measuring device which cooperates with all commonly used magnetization equipment such as an Epstein frame, single sheet yoke etc. The device delivers a sinusoidal voltage with programmable frequency and amplitude which is used to control a power amplifier supplying the magnetizing current. The following magnetic quantities are derived from the induced voltage in a secondary winding and from the voltage drop at a series shunt in the primary circuit or, alternatively, from a tangential field sensing coil: peak value of magnetic flux density, rms value of induced voltage, remanent induction, peak value of magnetic field strength, rms value of magnetic field strength, coercive field strength, and total maqnetic loss. All quantities are converted to dc voltages for analog readout and, after digitization, for computer storage. The time dependence of H(t) or dH(t)/dt and B(t) or dB(t)/dt can be sampled at up to 256 points per period, allowing the reconstruction of the hysteresis loop; thus all quantities can be obtained by analog and digital signal processing as well. The frequency range of the apparatus is 8 Hz to 1023 Hz.

3 citations