Per: MATEUS BOTANI DE Souza Dias (Departamento de Engenharia Metalúrgica e de Materiais - Escola politécnica da USP), David Pasello de Mendonça Bentancour (DEPARTAMENTO DE ENGENHARIA METALÚRGICA E DE MATERIAIS - ESCOLA POLITÉCNICA DA USP), Ramon Valls Martin (CTMetro - Centro de Metrologia Mecânica, Elétrica e de Fluidos, Instituto de Pesquisas Tecnológicas do Estado de São Paulo), Fernando José Gomes Landgraf (DEPARTAMENTO DE ENGENHARIA METALÚRGICA E DE MATERIAIS - ESCOLA POLITÉCNICA DA USP)
Abstract:
Economic growth of a country is related to its energy consumption. Therefore, it is important to find alternatives to reduce the electric energy waste in power grid. During the assembly and operation of transformers used to regulate the voltage at power grid, compressive stresses are applied at magnetic core sheets, increasing the losses and magnetostriction. As consequence, beyond the performance decreases, the transformer noise emission will increase. The present work investigates the effects of annealing under stress (TTT), 500°C, 300 N and 1200 s, on hysteresis loops (power loss) and magnetostriction of a grain oriented electrical steel submitted to compressive stresses. When compared with “as received sample”, the TTT reduced the power loss by -10%, -17%, -14%, -10%, -10% and -7% for the compressive stresses of 0, 2, 4, 6, 8 and 10 MPa at 0.7 T. However, the TTT had no influence at power loss for the test performed at 1.7 T. Regarding the magnetostriction, the reductions after the TTT, for the stresses of 0, 2, 4, 6, 8 and 10 MPa, were -6%, -49%, -49%, -16%, -22% and -12% (0.7 T) and -6%, -10%, -38%, -12%, -4% e 5% (1.7 T). In summary, the TTT is efficient to reduce the deleterious effects of compressive stresses, reducing the power loss and magnetostriction. Thus, this treatment could produce more efficient and quiet transformers.
