The resonance frequency method for fast approximation of the bandwidth of resistive-capacitive high voltage dividers

This paper introduces a novel method and calculation formula for fast approximation of the 3 dB bandwidth and frequency analysis of resistive-capacitive (RC) high-voltage (HV) dividers for power-quality measurement. The calculation formula brings stray inductance, resonance frequencies as well as voltage divider ratio and nominal capacitance values of the high-voltage and low-voltage unit into context, which allows the determination of achievable bandwidth of RC dividers. The novel method is potentially helpful when a frequency analysis based on Swept-Sine-Method cannot be conducted due to a large divider ratio in combination with a low input-voltage signal or for designing an RC voltage divider considering the bandwidth-limiting effects. The calculation formula is derived analytically by treating the RC divider as two simplified resonant series circuits. For acquisition of resonance frequencies, two measurement procedures are used and applied to an exemplary 100 kV-RC dividermodule. The formula is verified by comparing the results to a Swept-Sine-Method and AC circuit analysis. Measurement results indicate that the approximation contains low error when the novel method is combined with 2-port-like calibrated measurement of the dividers resonances.