Stray Magnetic Field around the Transformer

Distribution transformers installed in residential buildings should not disturb residents’ living comfort through noise, fire hazards and variable magnetic fields. The article presents the results of measurements concerning magnetic flux density having a frequency of 50 Hz in the space around oil-immersed transformers having a power of 1600 kVA, 800 kVA and 100 kVA as well as dry-type transformers having a power of 1600 kVA and 2500 kVA. Oil-immersed transformers generate magnetic induction at the same distance in the space outside the tank, approximately four times lower than that generated by dry-type transformers. Both in terms of oil-immersed and dry-type transformers, induction at a distance of 2 m away from the transformer is at the level of several μT and is approximately 10 times lower than values permissible for human presence. In terms of the variable flux density component of leakage, both oil-immersed and dry-type transformers can be installed in residential buildings.