Analysis on secondary single-phase grounding short circuit fault of voltage transformer

When single-phase of potential transformer secondary winding grounds, it raises the voltage of the other two non-fault phases. By measuring the impedance of secondary voltage cable and changing the grounding points, this paper analyzes and expatiates the reason is that the N-phase current of secondary electric cable generates voltage to the other two non-fault phases when grounding current affluxes it. The ways of preventing its effection to electric network are extending the section of N-phase electric cable or blocking the overvoltage protection.