A VI-based equipment for the frequency-domain characterization of voltage transformers

The presently employed methods for the measurement of the ratio and phase angle errors of the measurement transformers feature a high accuracy and sensitivity, but have been devised mainly to test the transformer´s behavior at its rated frequency. However, due to the increasing amount of distortion in the line signals in power systems, the knowledge of the transformers´ ratio and phase angle frequency responses can no longer be neglected. This paper proposes a test method, based on a Virtual Instrument, for the automatic determination of the ratio and phase angle errors of a voltage transformer in a frequency range up to 5 kHz. The results of some experimental work are reported, and the measurement accuracy is discussed