Design and performance of a wideband precision capacitive divider for AC and impulse voltage measurement

In this paper, the theoretical analysis, design, and performance of a wide-band precision capacitive voltage divider are presented. Based on the equivalent circuit model of the traditional capacitive divider, the influence factors of response characteristic and non-linearity are analyzed. The advantage of a compressed-gas capacitor as the high voltage part of the wide-band capacitive voltage divider is studied. The measured high voltage capacitance of the compressed gas capacitor is 9.854 pF. The theoretical value of the temperature coefficient is 2 ppm/°C, and the relative variation of the capacitance is -50 ppm with AC voltage (50 Hz) from 50 kV to 550 kV. The scale factor is estimated by AC voltage calibration, and the complete result of the calibration is expressed: F = 10 340(1% ± 0.026%) for a coverage probability of not less than 95% (k = 2). The step response and amplitude-frequency of the damped capacitive divider are analyzed and measured. Last but not least, the proposed capacitive divider prototype is tested to measure the switching impulse voltage and lightning impulse voltage. According to the test results, the proposed capacitive divider possesses good dynamic behavior and non-linearity and can measure the AC voltage, impulse voltage, and transient overvoltage in the field calibration.