Once ground fault occurs on DC transmission line or pole bus-bar

the neutral-bus arresters generatelarge energy. So the neutral-bus arrester with parallel multicolumn structure is designed. To avoid the valve on onecolumn of the arrester to absorb too much energy because of unequal current distribution

the uneven currentdistribution factor must be strictly controlled. The common method for judging current sharing performance of theparallel-multicolumn neutral-bus arrester is to test the uneven current distribution factor of the arrester under 100

1

000 Astandard lightning current and switching waveform. The natio

nal standard requires the uneven currentdistribution factor no larger than 1.1. However

the current amplitude and waveform of the neutral-bus arrester arequite different from those of test current. This study conducted current sharing test with consideration of typicalcurrent amplitude and waveform of the neutral-bus arrester

and analyzed the impacts of current amplitude andwaveform on current distributing performance. The results show that the uneven current distribution factor increasesgradually with the increase of impulse current in the range from 25 A to 500 A per column

and the currentwaveform has no effect on the current sharing performance of the valve of parallel multicolumn under low current.