In order to meet the needs of wideband voltage measurement such as recording power system fault waveforms and fault location by using partial discharge UHF sensor in gas insulated switchgear (GIS)

this paper designs a low-voltage arm circuit for partial discharge UHF sensor in GIS

and conducts experimental research on its characteristic. In the voltage division part

a two-stage capacitor voltage divider is applied to meet the requirements of high voltage division ratio and high frequency characteristic. In terms of improving low-frequency performance

this paper adds an impedance converter module after the output signal of the second-stage voltage division part. To filter the high-frequency oscillation caused by the sensor's own structure

a four-pole Sallen-Key low-pass filter is connected after the impedance converter module. The low-frequency characteristic of the measurement system can be acquired by measuring the exponential discharging signal fall time after charging. This paper designs a step pulse generator to obtain the high frequency cut-off frequency through step response. The output signal rise time of the generator is less than 5 ns

and the output voltage is adjustable from 5 000~30 000 V. Through experimental testing

the measurement system in this paper realizes a wideband transient voltage measurement with a bandwidth from 0.14 Hz to 9.1 MHz.