抄録
To cope with restructuring of electricity market, application of 22kV distribution systems to areas with high load density, is promising. To expand them, it is important to install 22kV distribution equipment on pavements and lots without fences. On the other hand, the neutral grounding method is expected for the 22kV distribution equipment in terms of rationalization of insulation. In this case, one line-to-ground fault current will be large. Therefore, to make safety of people, it is essential to decrease the contact voltage.
In this paper, we will perform the simulation of current distribution in the case of one line-to-ground fault and study the security of human from the viewpoint of both step voltage and contact voltage. We will also clarify that we can lower the contact voltage by grounding mutually insulated inner box and outer box separately. Then we will propose the improved grounding method.
