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Tools, Reference Materials, Resources and Basic Information for Learning Electrical Engineering Three phase induction motors are one of the most popular electric motors commonly found in processing plants or any manufacturing concern. They are used in situations where large power is required. The squirrel cage brand is the most popular and they perform various Because of the critical roles these motors play in any plant, a failure of the motor, inability to start, noisy operation and sundry other problems need to be remedied as soon as possible to avoid costly production downtime. The table below gives the commonly encountered problems in 3 phase squirrel cage induction motors, cause of problems and what remedy to apply to bring the motor back to production. This troubleshooting guide can also be applied to other types of three phase induction motors: Improper power supply Check to see that power supplied agrees with nameplate Improper line connections Check connections with wiring diagram supplied with motor Open circuit in winding or control switch This is normally indicated by a humming sound when switch is closed. Check for loose wiring connections. Confirm that all control contacts are closing. Mechanical failure Check to see that motor and drive turns freely. Check bearings and Short circuited stator Indicated by blown fuses.  Motor must be rewound Poor stator coil connections Remove end belts. Locate poor connections with test lamp. One phase may be open Check supply lines for open phase Check that nameplate voltage is maintained. Check connection. Fuses blown. Check overload relay, stator and push bu*tons Check for loose connections to line, to fuses and to control Motor does not come up to speed Motor is applied for the wrong application Voltage too low at motor terminals because of line drop Use higher voltage on transformer terminals or reduce load. Check Starting load too high Check load motor is supposed to carry at start.