Motors with Squirrel-Cage Rotors


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Motors with Squirrel-Cage Rotors
Motors with Squirrel-Cage RotorsLoss of output torque at rated speed in an induction motor may be due to open bars in the squirrel-cage rotor. To test the rotor and determine which rotor bars are loose or open, place the rotor in a growler. Engage the split-core ammeter around the lines going to the growler, as shown in Figure 9-14. Set the switch to the highest current range. Switch on the growler, and then set the test unit to the approximate current range. Rotate the rotor in the growler, and take note of the current indication whenever the growler is energized. The bars and end rings in the rotor behave similarly to a shorted secondary of a transformer. The growler windings act as the primary. A good rotor …
Citation
Mark R. Miller; Rex Miller: Robots and Robotics: Principles, Systems, and Industrial Applications. Motors with Squirrel-Cage Rotors, Chapter (McGraw-Hill Professional, 2017), AccessEngineering Export