Kiyoshi Wakimoto, MEIDENSHA CORPORATION
Substations located near residential districts in urban areas are required to use low-noise transformers. Noise generated by iron core vibration (excitation noise) has taken into consideration such factors as reduction of iron core magnetic flux density, improvement of material properties, iron core structure (joints/clamps) and residual strain by machining as part of the efforts to move forward with noise reduction. When excitation noise becomes quieter, noise accompanying load current (load current noise) sometimes becomes an issue after having been ignored while excitation noise was being dealt with.
Vibration of tanks that emit noise is considered that is transmitted through structural material or insulation oil to the tank. When the load current appears, the electromagnetic force occurs in the tank. As part of initiatives for predicting load current noise or noise reduction, we used JMAG for an analysis of electromagnetic force during current flow.
We will describe the examples of numerical analysis.