| ‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘ KAWASAKI STEEL TECHNICAL REPORT No.39 ( October 1998 ) Electrical Steel ‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘ |
| Analysis of Noise Emitted from Three-Phase
Stacked Transformer Model Core Masayoshi Ishida, Seiji Okabe, Keiji Sato |
| Synopsis: The influence of core structure and material on the noise level of a three-phase stacked transformer core is studied using model cores composed of high flux-density grain-oriented magnetic steels. The noise level at 1.7 T and 50 Hz decreases by slightly less than 2 dB with an increase of 0.01 T in B8 of the core material and is lower by 2 dB with step-lap joints than with alternate-lap joints. The amount of higher harmonics in magnetostrictive oscillation and magnetizing force of the core material show a strong correlation with the noise level. The vibration around the joints governs the noise level when the core is free of clamping pressure. The noise level decreases with increasing clamping pressure before reaching a minimum at a stress of about 0.05 MPa and then turns upward with further increase. The increasing rate of noise level is more moderate with step-lap joints than with alternate-lap joints. |
| TextiPDF: 7P/300kbj |