ABNORMAL SITUATIONS DURING OPERATION

MOTOR DOES NOT START

- Lack of voltage on motor terminals - Low feeding voltage
- Wrong connection
- Incorrect numbering of leads
- Excessive load
- Open stationary switch
- Damaged capacitor
- Auxiliary coil interrupted

LOW STARTING TORQUE

- Incorrect internal connection
- Failed rotor
- Rotor out of center
- Voltage below the rated voltage
- Frequency below the rated frequency - Frequency above the rated frequency - Capacitance below that specified
- Capacitors series connected instead of parallel

HIGH NO LOAD CURRENT

- Air gap above that specified- Voltage above that specified- Frequency below that specified- Wrong internal connection- Rotor out of center- Rotor rubbing on the stator- Defective bearing- Endbells fitted under pressure or badly fitted - Steel magnetic lamination without treatment - Run capacitor out of that specified- Stationary/centrifugal switch do not open

BEARING HEATING

-BEARING HEATING
- Excessive amount of grease
- Excessive axial thrust or radial force of the belt - Bent shaft
- Loose endbells or out of center
- Lack of grease
- Foreign bodies in the grease

MOTOR OVERHEATING

- Obstructed ventilation
- Smaller size fan
- Voltage or frequency out of that specified - Rotor rubbing on the shaft
- Failed rotor
- Stator with insufficient impregnation
- Overload
- Defective bearing
- Consecutive starts
- Air gap below that specified
- Improper run capacitor
- Wrong connections

HIGH NOISE LEVEL

- Unbalancing
- Bent shaft
- Incorrect alignment
- Rotor out of center
- Wrong connections
- Foreign bodies in the air gap
- Foreign bodies between fan and fan cover - Worn bearings
- Improper slots combination
- Inadequate aerodynamic

EXCESSIVE VIBRATION

- Rotor out of center
- Unbalance power supply voltage
- Failed rotor
- Wrong connections
- Unbalanced rotor
- Bearing housing with excessive clearance
- Rotor rubbing on the stator
- Bent shaft
- Stator laminations loose
- Use of fractional groups on run capacitor single-phase winding