Application of the inductive high current testing transformer for supplying of the measuring circuit with distorted current

TLDR: In this article, the authors determine the factors that condition the frequency band of operation of a high current testing transformer and limits the range of higher harmonics while testing of the transformation accuracy of instrument current transformers for distorted currents.

Abstract: The increasing number of non-linear loads and renewable energy sources causes a decrease in the power quality in the power networks. Therefore, tests of current transformers should be performed in similar conditions. This requires generation by a high current testing transformer of distorted currents that rms values are from a few hundred to several thousands of amperes with a given harmonics levels. However, its frequency band of operation is limited by inductances of its windings and connected load that result from the length and parameters of the used current track and connected device under test. To ensure the constant rms value of higher harmonic of distorted secondary current with the increase of its frequency proportional increase of the rms value of this harmonic in distorted primary voltage of the high current testing transformer is required. However, the maximum permissible value of primary voltage is limited by the dielectric strength of insulation of the primary winding. The purpose of presented studies is to determine the factors that condition the frequency band of operation of a high current testing transformer and limits the range of higher harmonics while testing of the transformation accuracy of instrument current transformers for distorted currents.