LV Motors / Ex-motors instructions 99-09 23
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 be required, please
contact the nearest ABB Sales Office.
Motor trouble shooting chart
Your motor service and any trouble shooting must be handled by qualified persons with 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 with diagram supplied with
motor.
Open circuit in winding or control Indicated by humming sound when switch is
switch 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 Indicated by blown fuses. Motor must be rewound.
Poor stator coil connection Remove end bells, locate with test lamp.
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 manufacturer.
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 Power failure Check for loose connections to line, to fuses and
dies down to control.
Motor does not come Not applied properly Consult supplier for proper type.
up to speed Voltage too low at motor terminals Use higher voltage or transformer terminals or
because of line drop reduce load. Check connections. Check
conductors for proper size.
Starting load too high Check load motor is supposes to carry at start.
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.
Motor takes too long to Excessive load Reduce load.
accelerate and/or draws Low voltage during start Check for high resistance. Adequate wire size.
high amp Defective squirrel cage rotor Replace with new rotor.
Applied voltage too low Get power company to increase power tap.
Wrong rotation Wrong sequence of phases Reverse connections at motor or at switchboard.
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