Abstract
With a recent size and weight reduction of electrical transformers, acoustic noise from transformers is likely to increase in a zone of audibility. Underlying technology for the acoustic noise reduction is required. Electrical transformers consist of iron cores, coils, tanks, frames and other structures. These vibration mechanisms and propagation path are unexplained clearly as a sound source. Investigation for each vibration characteristic is required to reduce the acoustic noise. In particular, as a sound source of electrical transformers, Understanding characteristics of an iron core are important. Experimental Modal Analysis (EMA) for a laminated iron core is performed with an impact hammer. EMA gives us the natural frequencies and vibration modes to reduce acoustic noise. Also we investigate a reliability of the Finite Element Method (FEM) models.
