Testing Squirrel Cage Rotors

A Quick guide to troubleshooting any issues with a squirrel cage rotor.

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Rotor Testing Guide

This is a must-read for any electric motor shop repair shop manager, technician, electrical engineer,
student, or maintenance personnel. Basically anyone working on or around electric motors needs to understand
how to troubleshoot any issues with a squirrel cage rotor.

In this timeless resource article, you will learn about testing methods to determine broken and loose bars,
voids in endrings, cracks, vibration, overheating, and much much more……

Open Rotor Bars
  • Most common reasons for squirrel cage rotor failure
  • Learn methods for testing a squirrel cage rotor which has failed or is near failure
  • How an induction rotor works
  • The problems broken rotor bars can create
  • 19 colored pictures and graphs
  • And much much more

Disassemble Motor Rotor Testing Methods

Open Rotor BarsVisual inspection of rotor failure:

  • Balancing issues
  • Cracked endrings
  • Melted aluminum or copper
  • Shifted laminations
  • Casting flaws in endrings and bars
  • Localized burnt spots
  • Open bars
  • And more

 

Testings methods

  • Growler testing for open bars
  • Coreloss testing for iron integrity
  • High current excitation testing for open bars
  • Spectrum analysis for vibration testing
  • Tap testing for loose bars
  • Dye penetration test for cracks
  • Temperature paint testing for hot spots
  • Ultrasonic testing for voids in endrings and cracks in the shaft
  • Low resistance ohmmeter testing for broken bars
  • High current low voltage transformer testing
  • Thermal imaging
Open Rotor Bars

Assembled Motor Rotor Testing Methods

Open Rotor Bars
  • Single-phase testing for open bars
  • Two ammeter comparison testing for open bars
  • Stroboscope testing for speed issues
  • Vibration analysis
  • Motor current signature analysis for open bars
  • Stray flux testing for open bars
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