ELF magnetic field measurement and calculation in 500 kV gas insulated substation

In this paper, we discussed the extremely low frequency (ELF) magnetic field environment in a 500 kV/275 kV gas insulated substation. We investigated magnetic field distribution around 3-phase GIS (gas insulated switchgear) by comparing the measurement results with calculation using finite element method (FEM). By simultaneous measurement of conductor current, we could have very good agreement of calculation results with measurement one. Particularly, the drastic mitigation of magnetic field with distance from GIS was characterized and quantified by comparing the one in open-air substation. In addition, the magnetic field distribution in GIS was discussed by analyzing the influence of induced current distribution in GIS sheath. From the results, we characterized the distinct features of magnetic field distribution in 500 kV/275 kV gas insulated substation by comparing with another type of substation.