Abstract: The common three main transformer neutral point protection methods were introduced, which are gap, lightning arrester and lightning arrester combined spark gap. The principle of zero sequence overcurrent protection in transformer neutral point gap was expounded, the earthing request of main transformer neutral point was described. In order to ensure rational operation and avoid operation hidden danger, the maters needing attention in transformer neutral point operation were given in this paper.

Key words: transformer, neutral point protection, gap over-current, operation