TROUBLE SHOOTING FOR L.V. MOTORS
Table 1-3 Troubleshooting
(1) Load is disconnected but motor doesn't rotate
Trouble | cause | Remedy |
Makes a groaning sound | Faulty switch contact Blown fuse One phase wire of the power supply open Stator coil open Stator and rotor touching due bearing wear | Adjust the contact Replace Replace Repair by a specialist Replace the bearing |
Starts in either direction when Turned by hand | Three-phase is operating as single-phase | Check the power source with a voltmeter |
Doesn't make any noise | Stator coil open Outside the motor · Power failure · Open connection wire · Faulty switch contact · Faulty starter contact | Repair by a specialist Contact the power company Check the source wiring Adjust the contact |
(2) Rotates, but:
Trouble | cause | Remedy |
Rotates in the wrong direction | Connection error | Change any two of the three phase source |
Fuse blows | Shorted lead wire | Replace |
Speed doesn't increase | Faulty star-delta starter contact | Adjust |
Groans | Over current Rotor and stator touching Overheating Rotor and stator touching | Repair by a specialist Replace the stator winding |
Make a high-pitched metallic noise | Faulty bearing | Replace the bearing |
(3) Rotates when the load is disconnected but when the load is connected it
Trouble | cause | Remedy |
Belt fly's off | Over load Driven machine doesn't rotate due to trouble Faulty installation or improper belt attachment | Drop to the rated load Adjust the driven machine Align the centers of the sheaves and correct the installation |
Switch over-heated | Insufficient switch capacity Overload | Replace with one having the rated capacity Drop to the rated load |
Fuse blows | Insufficient fuse capacity Overload | Replace with one having the rated capacity Drop to the rated load |
Overheats | Unbalance of power source Voltage drop Overload | Consult with the power company Drop to the rated load |
Speed suddenly drops | Voltage drop Overload | Consult with the power company Drop to the rated load |
Stops | Ball bearing damaged by over- heat | Replace the ball bearing |
Makes a funny noise during operation | Three-phase is operating as single-phase | Check the power source with a voltmeter |
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