Study on magnetic field distribution of 10 kV switchgear and shielding efficiency of enclosure

The power frequency magnetic fields have a potential adverse health effects on people and MV switchgear acts as one of the prominent sources of magnetic field in the substation. The magnetic field distribution around 10 kV switchgear and the shielding efficiency of the enclosure are studied in this paper. Based on the basic theory of electromagnetic field, the mathematical model of the power frequency magnetic field of switchgear is established. The magnetic induction intensity is solved by finite element method (FEM), and the mesh controlling method is discussed. The shielding efficiency of enclosure is calculated, and the influence of enclosure’s magnetic permeability and thickness on shielding efficiency is analyzed. Then the shielding improvement suggestions are put forward according to the calculation results. The results show that, when the distance from the switchgear door is less than about 0.6 m, the magnetic induction intensity may reach the public exposure limit 100 μT. With the increase of the relative magnetic permeability and the thickness of enclosure, the shielding efficiency is improved, but gradually stabilized.