Research on the Temperature Stability of the Electronic Voltage Transformer Based on Current

The temperature stability of an electronic voltage transformer (EVT) based on current was analyzed. It was presented that the high voltage capacitor and the integral circuit in the primary-side signal processing unit were two main influencing factors. The temperature compensation scheme that employing a number of capacitors with positive temperature coefficient and with the same value negative temperature coefficient in serial connection to comprise the high voltage capacitor was designed, which can improve the temperature stability of the high voltage sensor. The method of using the thermal resistor to compensate the temperature characteristic of the integral capacitor was proposed, reducing the error introduced by the temperature change. According to IEC60044-7, the accuracy versus temperature test on the developed 110 kV EVT prototype was carried out. The results show that the designed compensation schemes are effective and the EVT is compliant with the 0.2 measurement precision class over the temperature range from 40 ℃ to +70 ℃.