On account of the weak fault current and unstable fault arc, the problems of the single phase to ground fault line selection in the non-solid earthed network have never been thoroughly resolved.
由于故障电流小、电弧不稳定等原因，小电流接地系统单相故障选线问题始终没有得到彻底解决。
2
The characteristics of arc furnace are low voltage, big current and nonlinear load. Much negative sequence current is produced during running. As a result, the power net is unstable.
电弧炉具有低电压、大电流而且负荷非线性的特点，在其运行过程中产生大量的负序电流，导致电网不稳定。
3
Apply high voltage pilot arc and high frequency stable arc with constant current properties, prevent influence from unstable voltage of power grid.