8
LV Motors/Machine Instructions 10-2000
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 trouble shooting chart
Your motor service and any trouble shooting must be handled by qualified persons with 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 closed.
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, fuses and
dies down
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.
Motor overheats while
Overload
Reduce load.
running underloaded
Frame or bracket vents may be
Open vent holes and check for a continuous stream
clogged with dirt and prevent proper
of air from the motor.
ventilation of motor
Motor may have one phase open
Check to make sure that all leads are well
connected.
Grounded coil
Locate and repair.
Unbalanced terminal voltage
Check for faulty leads, connections and
transformers.