Effective Magnetic Shielding in Electric Arc Furnace Transformers Using Interphase Wall Shunts

Magnetic shielding in electric arc furnace (EAF) transformers is of a great importance for stray loss reduction in different structural parts of the transformer. Conventionally, magnetic wall shunts in front of each phase or wall shunts covering the entire tank wall are used to reduce stray losses on the tank walls. In this study, interphase magnetic wall shunt configuration for effective magnetic shielding in EAF transformers is introduced. The proposed wall shunt arrangement is very effective in stray loss reduction in EAF transformers and provides a low-cost alternative for conventional magnetic wall shunt designs. A 30 MVA three-phase EAF transformer is investigated as a case study and 2D finite element analysis (FEA) is used for evaluation of stray losses in different arrangements of magnetic shunts. Also, wall shunt losses are calculated using an analytical formulation of eddy-current losses for laminated steel material. The simulation results show that the proposed wall shunt arrangement can reduce the stray losses by 48% with 33% less weight compared to conventional arrangements where wall shunts are placed exactly in front of each phase.