Magnetic field disturbances of indoor MV/LV substations in Finland

At Tampere University of Technology (TUT), magnetic fields from indoor distribution substations have been studied for few years. A phone questionnaire study has been done about magnetic field reductions in substations, as a part of the studies about the distribution substation magnetic fields. The aim of this study was to find out about the magnetic field problems, the electric utilities might have had. Altogether 34 electric utilities were contacted in connection with this phone questionnaire. Questions about the possible magnetic field interference and different reduction methods were discussed in a telephone conversation. 31 of the utilities wished to answer the questions. The questions have included inquiries about possible magnetic field interference, customer complaints, different reduction methods, costs and of course the outcome of magnetic field reductions. Twelve of the utilities reported to have encountered problems caused by indoor MV/LV substation magnetic fields. Most of the utilities that had encountered these problems, had succeeded in reducing magnetic fields.