Surface Leakage Current Analysis of a 500 kV DC Voltage Divider under Natural Environmental Influences

In this work, a SMD-based 500 kV DC voltage divider is investigated for possible load scenarios of HVDC installations. For this purpose, the leakage current across the surface of the voltage divider's insulation is measured using long-term measurements over several days and short-term measurements with different voltage levels, with consideration of the weather situation. The measured leakage currents are analyzed quantitatively in order to evaluate the influence of the environmental conditions. Another aspect of the analyses are sequential voltage ramping tests with different voltage levels in order to investigate the effects on the insulation during the ramp-up and ramp-down of voltage levels. The results show that the leakage current on a wetted surface reacts significantly to changes in high relative humidity. Furthermore, additional alternating loads to the DC voltage, as is the case with ramp-up and ramp-down voltage changes, have a recognizable influence on the value of the leakage current.