9. Troubleshooting
These instructions do not cover all details or variations in equipment nor provide for every possible condition to be met in
connection with installation, operation or maintenance. Should additional information required, please contact the nearest
ABB Sales Office.
Motor troubleshooting chart
Your motor service and any troubleshooting must be handled by qualified persons who have proper tools and equipment.
TROUBLE
CAUSE
WHAT TO DO
Motor fails to start
Blown fuses
Replace fuses with proper type and rating.
Overload trips
Check and reset overload in starter.
Improper power supply
Check to see that power supplied agrees with motor rating plate and
load factor.
Improper line connections
Check connections against diagram supplied with motor.
Open circuit in winding or control switch Indicated by humming sound when switch is closed. Check for loose
wiring connections.
Also ensure that all control contacts are closing.
Mechanical failure
Check to see if motor and drive turn freely. Check bearings and
lubrication.
Short circuited stator
Poor stator coil connection
Indicated by blown fuses. Motor must be rewound. Remove end
shields, locate fault.
Rotor defective
Look for broken bars or end rings.
Motor may be overloaded
Reduce load.
Motor stalls
One phase may be open
Check lines for open phase.
Wrong application
Change type or size. Consult equipment supplier.
Overload
Reduce load.
Low voltage
Ensure the rating plate voltage is maintained. Check connection.
Open circuit
Fuses blown, check overload relay, stator and push buttons.
Motor runs and
then dies down
Power failure
Check for loose connections to line, to fuses and to control.
Motor does
not come up to
nominal speed
Not applied properly
Consult equipment supplier for proper type.
Voltage too low at motor terminals
because of line drop
Use higher voltage or transformer terminals or reduce load. Check
connections. Check conductors for proper size.
Starting load too high
Check the start load of the motor.
Broken rotor bars or loose rotor
Look for cracks near the rings. A new rotor may be required, as repairs
are usually temporary.
Open primary circuit
Locate fault with testing device and repair.
Low voltage motor manual 01-2009
| ABB Motors and Generators
EN-19
