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Examination of Eddy Current between Steel Sheets without Insulation and a Criterion for Determining the Necessity of Insulation
Author(s) -
Akagi Akira,
Takahashi Norio,
Nakano Masanori,
Doi Yuhito,
Miyagi Daisuke
Publication year - 2015
Publication title -
electrical engineering in japan
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.136
H-Index - 28
eISSN - 1520-6416
pISSN - 0424-7760
DOI - 10.1002/eej.22508
Subject(s) - eddy current , transformer , materials science , finite element method , core (optical fiber) , composite material , structural engineering , electrical engineering , engineering , voltage
SUMMARY In the laminated core of transformers, motors, and so on, each electrical steel sheet is usually insulated in order to reduce the eddy current loss. It has been reported that insulation is not necessary in such a laminated core under some conditions. However, few studies have been performed in the form of a quantitative and systematic examination of the relationship between the insulation and eddy current. In this study, the eddy current losses of a core made of SPCC (cold rolled steel sheets) of different widths with and without insulation under various conditions are analyzed using the finite element method (FEM) and with the contact resistance taken into consideration. The equivalent circuit of a laminated core without insulation is presented, and can be used for determining the necessity of insulation. It is shown that the increase in the eddy current is affected by the ratio of the resistance of the steel to the contact resistance. An experimental investigation is also carried out.