Levels of magnetic field in an apartment near 110/35 kV substation and proposal of mitigation techniques

The paper presents a real case of non-ionizing radiation testing in an apartment positioned next to "Belgrade 6" 110/35 kV substation. The measurements were performed in order to check the compliance of non-ionizing radiation levels in the apartment with the limits prescribed by Serbian regulations. The values of magnetic flux density obtained by measurements are significant due to very specific position of the apartment in relation to the substation, as both the apartment and the substation are located inside the same building. Moreover, the equipment in the substation is located very close to the apartment, essentially next to its wall and ceiling. Two main sources of the magnetic field in the apartment were identified on the basis of disposition of the equipment inside the substation. The first one are the 110 kV and 35 kV busbars located near the wall of the apartment, and the second one is the ripple control system located above the apartment. After the measurements were performed, some possible mitigation solutions based on passive shields were investigated by means of 3D simulations. The results of the measurements performed and the results of the shield design are shown in detail in the paper.