Design of a 400 kV resistive voltage divider with stray capacitance compensation for fast-front pulsed voltage

Accurate residual-voltage measurement of metal-oxide surge arresters requires a high-voltage divider with sufficient insulation strength, fast transient response, and electromagnetic-interference immunity. Conventional resistive voltage dividers (RVDs) exhibit good linearity and stability; however, at several hundred kilovolts, the stray capacitance between the high-voltage arm (HVA) and ground can distort fast transient waveforms and increase response time. In this work, a 400 kV-rated fast-response RVD with stray-capacitance compensation is developed for residual-voltage testing. A two-region compensation configuration is employed, comprising a sleeve-shaped inner conductor arranged near the grounded end of the HVA to reduce the effect of low-end stray capacitance, and a conical grading shield installed at the high-voltage terminal to introduce compensating capacitive coupling while improving the electric-field distribution. Finite-element electrostatic simulations and equivalent-circuit simulations are used to optimize the key structural parameters, including the height of the inner conductor and the height and width of the grading shield. Step-response experiments verify that the compensation structures effectively shorten the response time and suppress waveform distortion. An optimized RVD was fabricated and tested using a nanosecond square-wave source and a 1.2/50 μs impulse-voltage platform. The experimental results show that the RVD has a response time below 4.7 ns, withstands impulse voltages exceeding 400 kV, and has a calibrated voltage division ratio of 1018.62 with a maximum expanded relative uncertainty of ∼2.1% (k = 2) over the directly calibrated range of 30-180 kV. The proposed RVD provides a simple and engineering-applicable approach for fast-front residual-voltage measurement and the transient-performance improvement of high-voltage RVDs.