1原接地系统状况我公司是70年代初建成投产的化肥企业，初建时电气系统接地电容电流较小，采用6 kV中性点不接地方式，即小电流接地系统。随着企业的发展壮大，供电系统也越来越大，接地电容电流成倍增长。在中性点不接地系统中，由于单相接地故障并不破坏系统线间电压的对称性 1 The original grounding system conditions Our company is built and put into operation in the early 70s fertilizer companies, initially built when the electrical system grounding capacitor current is smaller, using 6 kV neutral ungrounded, that is, small current grounding system. With the development and growth of enterprises, power supply systems are also growing, ground capacitance and current doubled. In the neutral ungrounded system, due to single-phase ground fault does not undermine the symmetry of the system line voltage