Calibration of Burdens for Instrument Transformers

The first part of this paper deals with the influence of burden accuracy on the errors of current and voltage instrument transformers. The requirement stated in the prepared standard, corresponding to a tolerance of burden value B ± 3 % and power factor PF ± 0.02, is confronted with measurement results. The second part of the paper deals with the calibration process for instrument transformer burdens. This is followed by a description of the 3-voltmeter method for determining PF and apparent power B, including the measurement uncertainty calculation. A comparison is made between the achieved measurement uncertainties and the requirements stated in the prepared standard.