Current-transformer testing

Arnold, A.H.M.

doi:10.1049/jiee-1.1934.0064

Cited by 25 publications

(6 citation statements)

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“…The method most widely used to calibrate the transformers is to compare the transformer under test with a reference transformer that has the same nominal ratio and higher accuracy [5,6]. According to the International Electrotechnical Commission [7,8], the ratio error and phase displacement of a transformer under test should be measured by connecting an external burden to the secondary of the transformer under test.…”

Section: Introductionmentioning

confidence: 99%

Poling Field Dependence of Ferroelectric Properties and Crystal Orientation in Rhombohedral Lead Zirconate Titanate Ceramics

Ogawa¹,

Nakamura²

1998

Jpn. J. Appl. Phys.

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Methods to measure the burdens of voltage transformers (VTs) and current transformers (CTs) in situ in instrument transformer test systems have been developed using non-reactive resistors connected in series with the VT secondary and in parallel with the CT secondary. This development was based on a theoretical analysis of the equivalent circuits of the instrument transformers. The burden values for the instrument transformers are obtained by measuring the ratio error (and phase displacement) with varying resistors. The values of the transformer burdens obtained using this method were consistent, within acceptable tolerances, with those measured using conventional methods.

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Section: Introductionmentioning

confidence: 99%

Poling Field Dependence of Ferroelectric Properties and Crystal Orientation in Rhombohedral Lead Zirconate Titanate Ceramics

Ogawa¹,

Nakamura²

1998

Jpn. J. Appl. Phys.

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“…The EMPIR initiative is co-funded by the European Union's Horizon 2020 research and innovation programme and (CTs) are usually connected with their input terminals at high potential. High-accuracy calibration of the complex current ratio of CTs, i.e., their current ratio error and phase displacement, is already well established for many decades [1]- [9]. However, to obtain sufficiently low uncertainties for such calibrations, the CTs under test are usually calibrated under idealized reference conditions, that is, with a nondistorted sine wave and with the primary terminals at ground potential.…”

Section: Introductionmentioning

confidence: 99%

Voltage Dependence of the Reference System in Medium- and High-Voltage Current Transformer Calibrations

Brom

Leeuwen

Rietveld

et al. 2021

IEEE Trans. Instrum. Meas.

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A sampling current ratio measurement system has been developed to calibrate the voltage dependence of the ratio error and phase displacement of current transformers (CTs) used for medium-voltage (MV) and high-voltage (HV) applications. The influence of the voltage-induced leakage current on the apparent ratio error and phase displacement of the reference circuit was unambiguously demonstrated using a novel measurement method. Measurement results for voltages up to 24 kV show that the observed leakage current is purely capacitive and caused by the shielded cable capacitance of the HV cable used to feed the current. The maximum ratio error and phase displacement were found to be about 100 parts in 10 6 and 100 μrad for the smallest current of 100 A used for these investigations. Since these values scale linearly with the applied voltage and inversely proportional with current, the assumption of negligible voltage dependence used in other reference systems presented in literature is questionable. Using the corrected reference circuit, a commercial class 0,2S MV CT with 2500 A nominal current was calibrated at voltage levels up to 24 kV. The voltage dependence of the ratio error and phase displacement for primary currents up to 500 A was demonstrated to be capacitive as well, with a maximum impact on the current ratio of almost 0.9 % for a primary current of 100 A (corresponding to 3.6 % at 1 % of nominal current). This value is beyond the limits of in-force standards, which emphasizes the necessity of implementing voltage dependence testing in those standards.

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“…The method most widely used to measure CT errors is to connect the reference apparatus in series with the CT being measured before installation or with an interruption in the service, and then comparing it with a reference transformer that has the same nominal ratio and higher accuracy [14,15], which is usually called the comparison measurement method. The ratio and phase errors of the CT being measured are accurately determined by comparing its secondary current with that of a reference transformer with a higher level of accuracy.…”

Section: Introductionmentioning

confidence: 99%

Method for online measurement of optical current transformer onsite errors

Zhao¹,

Yang²,

Lu³

et al. 2016

Meas. Sci. Technol.

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This paper describes a method for the online measurement of an optical current transformer (OCT) onsite errors comparing with a conventional electromagnetic current transformer (CT) as the reference transformer. The OCT under measurement is connected in series with the reference electromagnetic CT in the same line bay. The secondary output signals of the OCT and the electromagnetic CT are simultaneously collected and processed using a digital signal processing technique. The tests developed on a prototype clearly indicate that the method is very suitable for measuring errors of the OCT onsite without an interruption in the service. The onsite error characteristics of the OCT are analyzed, as well as the stability and repeatability.

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Current-transformer testing

Cited by 25 publications

References 0 publications

Poling Field Dependence of Ferroelectric Properties and Crystal Orientation in Rhombohedral Lead Zirconate Titanate Ceramics

Poling Field Dependence of Ferroelectric Properties and Crystal Orientation in Rhombohedral Lead Zirconate Titanate Ceramics

Voltage Dependence of the Reference System in Medium- and High-Voltage Current Transformer Calibrations

Method for online measurement of optical current transformer onsite errors

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