Precise measuring system for traceability of high current transformer standards

Surdu, M. N.; Ornatsky, O.A.; Mukharovsky, M.J.; Melestuk, D.V.; Kopshyn, V.V.; Kikalo, V.N.

doi:10.1109/cpem.2008.4574894

Cited by 1 publication

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“…Conventional calibration methods generally use the electromagnetic CT with an iron core [5][6][7][8][9][10][11][12][13]. However, the iron core is easily saturated at high currents, unless a bulky iron core is used which encounters manufacturing difficulty.…”

Section: Introductionmentioning

confidence: 99%

A high-current calibration system based on indirect comparison of current transformer and Rogowski coil

Luo

et al. 2013

Meas. Sci. Technol.

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The calibration of the protective current transformer (CT) is of particular importance, since its accuracy at high currents is crucial to the correct operation of the subsequent relay protection devices. Conventional calibration methods have been using an electromagnetic CT which contains an iron core as the standard CT. The iron core is big and difficult to manufacture for high-current measurement, and the serious residual magnetism of the iron core at high currents can lead to excessive measurement errors. This paper proposes a calibration system based on indirect comparison of CT and Rogowski coil, i.e. using an iron-core CT to correct the error of the Rogowski coil at low currents, which may be caused by the position of the current-carrying conductor and so on, and then using the calibrated Rogowski coil as the standard transformer at high currents for its good linearity and wide dynamic range, and there is no magnetic saturation. Since the output of the Rogowski coil needs to be integrated, an improved digital integrator based on direct current (dc) negative feedback is adopted, which can effectively eliminate the influences of temperature drift, time drift and dc offset caused by the analogue circuit. The measurement errors of each part of the calibration system have also been discussed, and the test results show that the accuracy of the system can reach up to the 0.05S Class and the uncertainties are 0.038% for ratio and 0.68′ for phase in the range 500 A to 50 kA.

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Section: Introductionmentioning

confidence: 99%

A high-current calibration system based on indirect comparison of current transformer and Rogowski coil

Luo

et al. 2013

Meas. Sci. Technol.

View full text Add to dashboard Cite

show abstract

Precise measuring system for traceability of high current transformer standards

Cited by 1 publication

References 0 publications

A high-current calibration system based on indirect comparison of current transformer and Rogowski coil

A high-current calibration system based on indirect comparison of current transformer and Rogowski coil

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