Research on Measuring Range Extension Method of Voltage Transformer

Generally, voltage transformers can only work in a certain rated voltage level. To cover a wide measuring range, it is necessary to develop several voltage transformers with different voltage levels. This paper introduces a voltage transformer with wide measuring range based on series and parallel of primary windings. The primary winding of the transformer is composed of four sections of the same winding, which can work in three modes: 10 kV, 20 kV and 40 kV. The secondary winding consists of five independent windings, which are combined with three modes of the primary winding to achieve 15 different voltage ratios. Through error calibration, the errors of all voltage ratios are less than the ratio error of 20 × 10–6 and the phase error of 20μrad. The accuracy level meets the requirement of 0.002 level. The measuring range of the voltage transformer is 1 kV to 48 kV, which can cover the whole range of medium voltage. It has certain reference value for improving the measuring range of the voltage transformer and reducing the cost, and has a good popularization and application prospect.