A Reference Resistive Voltage Divider for Switching Impulses

Published in 2015

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Summary

Reference voltage dividers are essential for ensuring measurement accuracy of high voltage tests, including tests with high-voltage switching impulses. This paper describes the design and performance of a portable reference resistive voltage divider for the switching impulse voltage with a rated voltage of 400 kV. This design uses discrete resistor elements for the high voltage arm, which allows easier and more compact construction than a single bifilar wire-wound high-voltage resistor. The modular design allows convenient assembling and disassembling of the divider for transport and on-site calibrations. The high-voltage arm resistors are housed in a sealed cylindrical tube filled with low-pressure SF6 gas to avoid discharge from the surfaces of resistor elements. A damping resistor is placed at the far end of the lead connected to the input of the divider in order to reduce oscillation due to the transmission line effect. The low-voltage arm is as compact as possible for minimal inductance. A capacitor is connected in parallel with the low-voltage arm resistor to compensate the stray capacitance of the high-voltage arm to improve the step response of the divider. Experimental results for the voltage ratio of the divider determined by resistance measurement and low voltage DC measurement are given. Experimental results show that an Experimental Response Time of 0.22 µs and a Settling Time of 3.0 µs have been achieved. No overshoot is present in the step response. These characteristics indicate that the divider can be used as a reference for the standard switching impulse voltage required by the relevant IEC standard. Results of a high-voltage comparison test of the developed resistive voltage divider with a damped capacitor divider are also presented.