NDLI: Relevance of magnetostriction and forces for the generation of audible noise of transformer cores

Content Provider	IEEE Xplore Digital Library
Author	Weiser, B. Pfutzner, H. Anger, J.
Copyright Year	1965
Abstract	Recently, the two most significant characteristics of power transformer cores, i.e., loss and noise, have been reduced considerably because of improved material and improved core design. An undisputed base value of noise results from magnetostriction (MS) due to the global magnetization of limbs and yokes, whereas excess values are attributed to different mechanisms, such as excess MS and magnetic forces (MF), in a controversial way. However, a multistep lap (MSL; number of overlap steps N>1) yields considerably lower noise than a single-step lap (SSL; N=1), indicating a specific role of joint design. The present work was aimed at a deeper understanding as a tool for further improvements. For a large number of differently built-up single-phase model cores, local distributions of surface displacements d/sub x/, d/sub y/, d/sub z/ and velocities v/sub x/, v/sub y/, v/sub z/ as well as the corresponding noise n were determined. As a major finding, MSL yielded weak reductions of in-plane vibrations v/sub x/ and V/sub y/, considerable reductions of v/sub z/, and strong reductions of n. Interpretations of results were based on numerical Spice modeling of linearized joint vibrations, which were also established experimentally. The results indicate high values of off-plane flux density B/sub z/ and the corresponding Maxwell stress arising at the outermost sheet ends for SSL, and considerably lower values for MSL, provided that B is below its critical value B/sub c/. MSL yielded reductions of d/sub z/, v/sub z/, and n in 80% of all cases. Three additional core parameters-small air gap lengths, high overlap lengths, and high lamination factors A-all lead to reduced n; the use of oil yielded strong reductions. It is concluded that joint designs actually play a predominant role in noise generation. Apart from some contribution from attractive in-plane forces due to B/sub z/, in air gaps, interlaminar flux B/sub z/ yields primary sources of vibrations that propagate to the entire core surface. In core regions of reduced /spl Lambda/, B/sub z/ yields vibrations of sheet ends due to MF according to an experimentally determined effective Young's modulus that considers practical conditions like waviness, burrs, and thickness variations of laminations. For high h, oscillations of the whole core thickness due to B/sub z/-caused MS will arise close to joints. For MSL, all of these mechanisms become less relevant: Gap regions show much lower B/sub x/ and, provided B
Sponsorship	IEEE Magnetics Society
Starting Page	3759
Ending Page	3777
Page Count	19
File Size	689486
File Format	PDF
ISSN	00189464
Volume Number	36
Issue Number	5
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2000-09-01
Publisher Place	U.S.A.
Access Restriction	One Nation One Subscription (ONOS)
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Magnetostriction Transformer cores Magnetic cores Magnetic noise Power transformers Magnetization Lamination Assembly Noise reduction Magnetic materials
Content Type	Text
Resource Type	Article
Subject	Electronic, Optical and Magnetic Materials Electrical and Electronic Engineering

Sl.	Authority	Responsibilities	Communication Details
1	Ministry of Education (GoI), Department of Higher Education	Sanctioning Authority	https://www.education.gov.in/ict-initiatives
2	Indian Institute of Technology Kharagpur	Host Institute of the Project: The host institute of the project is responsible for providing infrastructure support and hosting the project	https://www.iitkgp.ac.in
3	National Digital Library of India Office, Indian Institute of Technology Kharagpur	The administrative and infrastructural headquarters of the project	Dr. B. Sutradhar bsutra@ndl.gov.in
4	Project PI / Joint PI	Principal Investigator and Joint Principal Investigators of the project	Dr. B. Sutradhar bsutra@ndl.gov.in Prof. Saswat Chakrabarti will be added soon
5	Website/Portal (Helpdesk)	Queries regarding NDLI and its services	support@ndl.gov.in
6	Contents and Copyright Issues	Queries related to content curation and copyright issues	content@ndl.gov.in
7	National Digital Library of India Club (NDLI Club)	Queries related to NDLI Club formation, support, user awareness program, seminar/symposium, collaboration, social media, promotion, and outreach	clubsupport@ndl.gov.in
8	Digital Preservation Centre (DPC)	Assistance with digitizing and archiving copyright-free printed books	dpc@ndl.gov.in
9	IDR Setup or Support	Queries related to establishment and support of Institutional Digital Repository (IDR) and IDR workshops	idr@ndl.gov.in

Magnetic forces and magnetostriction in electrical machines and transformer cores

Reduction of Vibration and Sound-Level for a Single-Phase Power Transformer With Large Capacity

Flux distribution and power loss in the mitered overlap joint in power transformer cores

Measurement of spacecraft power transformer acoustic noise

A novel method of reducing iron losses in power transformer cores

Comparison of Magnetostriction Models for Use in Calculations of Vibrations in Magnetic Cores

The transformer characteristics of Orientcore HI-B

Effect of clamping stress on power loss in POWERCORE strip and Si-Fe transformer cores

Rotational Magnetization in Transformer Cores—A Review

Relevance of magnetostriction and forces for the generation of audible noise of transformer cores

Similar Documents

Magnetic forces and magnetostriction in electrical machines and transformer cores

Reduction of Vibration and Sound-Level for a Single-Phase Power Transformer With Large Capacity

Flux distribution and power loss in the mitered overlap joint in power transformer cores

Measurement of spacecraft power transformer acoustic noise

A novel method of reducing iron losses in power transformer cores

Comparison of Magnetostriction Models for Use in Calculations of Vibrations in Magnetic Cores

The transformer characteristics of Orientcore HI-B

Effect of clamping stress on power loss in POWERCORE strip and Si-Fe transformer cores

Rotational Magnetization in Transformer Cores—A Review

Relevance of magnetostriction and forces for the generation of audible noise of transformer cores