The Potential Gradient of Ground Surface according to Shapes of Mesh Grid Grounding Electrode using Reduced Scale Model (特集:平成17年〔電気学会〕電力・エネルギー部門大会)

In order to analyze the potential gradient of ground surface of grounding system installed in buildings, the hemispherical grounding simulation system has been designed and fabricated as substantial and economical measures. Ground potential rise (GPR) has been measured and analyzed for shapes of a mesh grid grounding electrode by using the system. The system is apparatus to have a free reduced scale for conductor size and laying depth of a full scale grounding system. When a current flows through a grounding electrode, the system is constructed so that a shape of equipotential surface is nearly identified a free reduced scale model with a real scale model.The system was composed of a hemispherical water tank, AC power supply, a movable potentiometer, and test grounding electrodes. The water tank was made of stainless steel and its diameter was 2m. AC power supply produced earth leakage current. GPR was measured by a moving probe of a potentiometer horizontally. The test grounding electrodes were fabricated through reducing grounding electrode installed in real buildings such as a mesh grid type, a combined type and so on. GPR has been measured in real time when a test current has flowed through grounding electrode. GPR was displayed in two-dimensional profile and was analyzed for shapes of a grounding electrode. When a mesh grid type was associated with a rod type and auxiliary mesh electrodes were installed at the four sides of mesh grid grounding electrode, GPR was the lowest of all test grounding electrodes. The proposed results would be applicable to evaluate GPR in the grounding systems, and the analytical data can be used to stabilize the electrical installations and prevent the electrical disasters.