AC and switching impulse performance of an ice-covered metal oxide surge arrester

Artificial ice tests were conducted for the first time with a high voltage metal oxide surge arrester (MOA) consisting of two units in series. The behaviour of the MOA under glaze ice was studied with AC voltage and switching impulse current surges. The AC voltage test results showed that an unevenly ice-coated MOA may be thermally stressed due to the leakage current transition from the ice covering of one unit to the interior of another unit not covered with so much ice. Whether the stressed unit stands up to this situation or not depends on the thermal properties of the unit and the duration of the active arcing period. With impulse current surges the residual voltage across an ice-covered unit may easily cause a flashover. This leads to a sudden increase in the surge current. With the MOA studied the current peak was over twice the value of normal operation, which stressed the lower unit operating normally.