Testing of HVDC arresters according to new IEC standard with emphasis on effect from operating voltage

Surge arresters in HVDC converter stations are subjected to continuous operating voltages with very different waveforms compared to arresters for normal a.c. applications. Since the protection levels achievable are directly proportional to how high the arresters can be stressed continuously, accurate knowledge of long-term stability and continuous power losses for the applied voltage waveforms are decisive. In the past it has been difficult to produce and perform tests on metal-oxide (MO) resistors with these waveforms, but today they can be readily produced by a high-voltage power amplifier system. More accurate knowledge of the performance of the MO resistors thus forms the basis for obtaining accurate designs of the arresters.