SOLUTION

If a single-phase induction motor runs slower than normal, the most likely defect is Worn bearing.

Causes of the slow speed of induction motor:

Following are the causes due to that speed of induction motor is slow:

• Increase in load
• Worn bearing
• Incorrect coupling of shaft
• Wrong alignment of the shaft motor
• Low supply voltage

Worn bearing: Bearing wear is another common fault in electric motors. As the motor ages, the bearing will change shape due to an imbalance of the motor or just fragmentation of the bearing itself. These deformations cause vibrations that increase the friction between shaft and motor, this will rise in temperature and decreases the speed of the motor as the rotor turns and eventually contribute to failures in other parts of the motor.

Shorted running winding: When running winding is shirted then excessive current is flow and the motor will burn.

Open starting winding: When starting winding of the induction motor is open then the motor is not started.

Insulation failure:- Insulation failure of the motor windings is a common incipient fault in electric motors. The windings of a motor are insulated to prevent shorting of the winding turns. This insulation is categorized into several classes which are rated for different maximum operating temperatures.

Improper fuses: Due to improper fuses, the motor is not started.

Note: Ball bearings reduce friction in machinery by presenting a minimal surface area

Many worn wheel bearings make noise and also decrease speed