The book chapter focuses mainly on transformer noise but includes a brief review of the main aspects of rotating machine noise, particularly where magnetic sources are relevant. An introduction to acoustic noise and core vibration terminology and analysis, which is applied in electrical machine noise and vibration studies is also given.

Chapter Contents:

• 10.1 Noise and vibration terminology and analysis
• 10.1.1 Acoustic noise
• 10.1.2 Surface vibration
• 10.1.3 Resonance effects in electrical steel and transformers
• 10.2 Historical perspective of transformer noise
• 10.3 Measurement of no-load and load noise
• 10.4 Magnetic core noise
• 10.5 Origins of magnetic core vibration
• 10.5.1 Dimensional changes due to magnetostriction
• 10.5.2 Dimensional changes due to Maxwell forces
• 10.5.3 Combined effects of magnetostriction and Maxwell forces
• 10.5.3.1 A simple approach to separating sources of vibration
• 10.6 Correlation between magnetostriction, core vibration and noise
• 10.6.1 Top and side surfaces
• 10.6.2 Front surface
• 10.6.3 Magnetostriction characteristics
• 10.7 Effect of phase displacement on noise of 3-phase transformer cores
• 10.8 Effect of core design and material on noise
• 10.8.1 Core material
• 10.8.2 Corner overlap length
• 10.8.3 Number of steps
• 10.8.4 Number of laminations per step
• 10.8.5 T-joint configuration
• 10.8.6 Clamping stress
• 10.9 Modelling and analysis of core vibration
• 10.10 Amorphous material in power transformers
• 10.11 Reduction of noise of transformer cores
• 10.12 Acoustic noise from rotating electrical machines
• 10.12.1 Background
• 10.12.2 Role of magnetostriction
• 10.12.2.1 Effect of rotational magnetostriction on core deformation
• 10.12.2.2 Noise of machines subjected to non-sinusoidal voltage excitation
• References

Inspec keywords: noise abatement; machine theory; turbomachinery; acoustic noise; transformer cores; vibrations

Other keywords: core vibration terminology; rotating machine noise; electrical machine core vibration; acoustic noise; vibration studies; magnetic sources; noise; transformer noise; electrical machine noise

Subjects: Magnetic cores; Sonics and ultrasonics; Transformers and reactors; Inductors and transformers