engleski

Quality Control of Squirrel Cage Rotors

The paper describes the concept of experience with a new control system for the measurement of the rotor bar conductivity (resistance) in large and medium size squirrel cage rotors of AC machines. The working principle is based on the detection and analysis of a signal which is proportional to the induced current and which is generated in the bar of the rotor cage by a specially designated excitation sensor. All the typical faults in rotor, like broken or interrupted rot or bars, poor or broken contact between bar and end ring, bad soldering joints, porosity in cast aluminium, incorect skew, poor or variable aluminium alloy quality, leakage, between laminations and glueing of bars to laminations, can be detected with the new system. Since the bars in the one rotor should be of equal quality a reference exists in the rotor itself. The reference data of one bar are taken and stored and the used for comparison with other rotor bars. Special criteria have been developed to analyze and categorize the rotor quality or condition. Software has been designated to facilitate the testing, documentation and analysis process. Case histories will be shown to illustrate the effectiveness of this new system for the quality control of squirel cage rotors in the manufacturing, repair and maintance of AC electic motors.

Induction Motor; Rotor Cage; Quality Control; Rotor Design; Cage Faults; Measurement System; Quality Criteria; Diagnosis; Software

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