A Shielded High Resistance Reference Voltage Divider for Switching Impulse Voltage Measurements

Abstract

Currently, IEC publications 60-3, 4 are being revised. In the revised draft of the International Standard, a new calibration method will be introduced. It was summarized as follows; The accuracy of most industrial measuring systems is maintained by means of comparison test against “Reference Measuring Systems”.
This paper describes an excellent reference divider for switching impulse voltage measurements. Switching impulse voltages are measured generally with capacitance voltage dividers. However, in this study, a shielded resistance divider with a very high resistance value (200kΩ) was developed as a prototype reference divider. The high voltage arm of the divider is a wire-wound resistor with very low temperature-resistance coefficient. In order to improve the response characteristics, a suitable shielding electrode was attached to the high voltage arm. The shielding electrode makes the potential distribution near the high voltage arm uniform and the capacitance of the high voltage arm to earth much decreases. Therefore, the response characteristics of the divider were improved drastically regardless of the very high resistance value. The measured response time of this divider was about 14 ns.
An excellent shielded high resistance reference divider with rated voltage of 500kV for switching impulse voltages has been developed.