Characterization of Parasitic Influences in a Wide-Bandwidth High Voltage Divider for Very Fast Transient Measurements

Abstract

Very Fast Transients (VFTs) are high-frequency, steep-fronted voltage impulses that occur in high-voltage power systems and advanced power electronic applications. VFTs possess short rise times down to a few nanoseconds and peak voltages up to hundred kilovolts, they can cause potential degradation and failure in system insulation, equipment, and measurement technology. High frequency ranges (above 300 MHz) and amplitudes render accurate measurements of voltage transients challenging, and existing literature lacks in standardization and traceability. VTT Technical Research Center of Finland developed a resistive divider designed for capturing puncture test waveforms with amplitudes of 600 kV and 5 ns rise time. In this paper, the divider is evaluated for rise time measurements of pulsed waveforms with rise times below 5 ns, identifying the effect of measurement environment and parasitics, and optimizing the design to improve the performance. After the analysis, the modified design is capable of measuring pulses with rise times as fast as 1 ns with an estimated voltage rating of 300 kV. Thermal management considerations are also performed to ensure the resistive components can withstand the pulsed energy losses.