Method for detection of broken bars in induction motors

Author

Dobrodeyev, Pavel N. ; Volokhov, Sergey A. ; Kildishev, Alexander V. ; Nyenhuis, J.A.

Author_Institution

Div. of Magnetism, Acad. of Sci., Kharkov, Ukraine

Volume

36

Issue

5

fYear

2000

fDate

9/1/2000 12:00:00 AM

Firstpage

3608

Lastpage

3610

Abstract

A method and apparatus for detection of broken bars in the rotor of a squirrel cage induction motor are described. The test method is easy to implement, no electrical connections need be made to the rotor, and it is not necessary to turn the rotor. The effect of the broken bar is modeled as an image current in a direction opposite to the current if it were intact and a corresponding returning image current in the other bars. Sense coils encompassing 180 degrees are examined, the inner coil is wound in the slots near the gap and the outer coil is on the outside of the stator. The main signal induced in the sense coils is due to the image currents associated with the broken bar. The signal induced in the coils is greatest when the broken bar is near the edge of the sense coils. A test apparatus with 8 poles and 24 slots was constructed and results of measurements on a rotor with 17 intact and one broken bar are presented. The inner and outer sense coils yield complementary information on the state of the rotor

Keywords

coils; fault diagnosis; machine testing; magnetic sensors; nondestructive testing; rotors; squirrel cage motors; NDT; broken bars detection method; cage model; discrete bars; image current; inner sense coils; outer sense coils; rotor testing; squirrel cage induction motor; test apparatus; virtual current model; Bars; Coils; Current density; Current distribution; Induction motors; Integral equations; Magnetic fields; Nondestructive testing; Rotors; Stators;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/20.908916

Filename

908916