Utilization of Two Sensors in Offline Diagnosis of Squirrel-Cage Rotors of Asynchronous Motors

Petr Kacor,Petr Bernat,Petr Moldrik

doi:10.3390/en14206573

Abstract

In the manufacture squirrel-cage rotors of asynchronous motors, a high standard of quality is required in every part of the production cycle. The die casting process usually creates porosity in the rotor bars. This most common defect in the rotor often remains hidden during the entire assembly of the machine and is usually only detected during final testing of the motor, i.e., at the end of the production process. This leads to unnecessary production costs. Therefore, the aim is to conduct a continuous control immediately after the rotor has been cast before further processing. In our paper, we are interested in selecting a suitable method of offline rotor diagnostics of an asynchronous motor that would be effective for these needs. In the first step, the selection of the method and its integration into the overall manufacturing process is carried out. The arrangement of the sensors and their calibration is then simulated on a 2D Finite Element Model of the rotor. The proposed offline measurement procedures and technologies are finally validated by testing measurements on a rotor that simulates the most frequently occurring faults. A test system is also developed that provides the operator continuous information about the running rotor measurements and makes it easier to evaluate the quality of the cast rotor by means of graphical visualization of the faults.

Highlights

In the production of asynchronous machine rotors, we often encounter the need to test their manufacturing quality during production
The magnetizing yoke that generates the static magnetic field is located near the rotor
The magnetic field lines from excitation yoke closed near the rotor

Summary

Introduction

In the production of asynchronous machine rotors, we often encounter the need to test their manufacturing quality during production This type of testing can detect a production defect in the rotor early on, immediately after the rotor has been cast and removed from the die casting mold. Otherwise, this defect would only appear at the end of the manufacturing process of the electric motor during its output testing [1,2]. This defect would only appear at the end of the manufacturing process of the electric motor during its output testing [1,2] In this case, the motor is still repairable by total rotor replacement. These include the pressing of the shaft into the stator pack, the adjustment of the rotor dimensions and its surface, the overall balancing of the rotating masses, the pressing of the bearings onto the shaft, and its final fixing to the frame with the stator [2]

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