Troubleshooting - ABB MT serie Installations- Betriebs Und Wartungshandbuch

6. 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 Offi ce.
Motor troubleshooting chart
Your motor service and any troubleshooting must be handled by qualifi ed persons with proper tools and equipment.
TROUBLE
Motor fails to start
Motor stalls
Motor runs and then
dies down
Motor does not come up
to speed
Motor takes too long to
accelerate and/or draws
high amp
Wrong rotation
GB –
12
CAUSE
Blown fuses
Overload trips
Improper power supply
Improper line connections
Open circuit in winding or control
switch
Mechanical failure
Short circuited stator
Poor stator coil connection
Rotor defective
Motor may be overloaded
One phase may be open
Wrong application
Overload
Low voltage
Open circuit
Power failure
Not applied properly
Voltage too low at motor terminals
because of line drop
Starting load too high
Broken rotor bars or loose rotor
Open primary circuit
Excessive load
Low voltage during start
Defective squirrel cage rotor
Applied voltage too low
Wrong sequence of phases
WHAT TO DO
Replace fuses with proper type and rating.
Check and reset overload in starter.
Check to see that power supplied agrees with
motor rating plate and load factor.
Check connections with diagram supplied with
motor.
Indicated by humming sound when switch is
closed. Check for loose wiring connections.
Also, ensure that all control contacts are closed.
Check to see if motor and drive turn freely.
Check bearings and lubrication.
Indicated by blown fuses. Motor must be
rewound. Remove end bells, locate with test
lamp.
Look for broken bars or end rings.
Reduce load.
Check lines for open phase.
Change type or size. Consult manufacturer.
Reduce load.
Ensure the rating plate voltage is maintained.
Check connection.
Fuses blown, check overload relay, stator and
push buttons.
Check for loose connections to line, to fuses and
to control.
Consult supplier for proper type.
Use higher voltage or transformer terminals
or reduce load. Check connections. Check
conductors for proper size.
Check load motor is supposed to carry at start.
Look for cracks near the rings. A new rotor may
be required, as repairs are usually temporary.
Locate fault with testing device and repair.
Reduce load.
Check for high resistance. Adequate wire size.
Replace with new rotor.
Get power company to increase power tap.
Reverse connections at motor or at switchboard.
ABB / Low Voltage Motors / Manual 12-2004