LOW VOLTAGE MOTORS - Installation, operation, maintenance and safety manual - rev. 01 - 1.07.2016
21
TROUBLE CAUSE SOLUTION
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
Motor takes
too long to
accelerate and/
or draws high
current
Excessive load Reduce load
Low voltage during start Check for high resistance,make sure that adequate cable size is used
Defective squirrel cage rotor Replace with new rotor
Applied voltage too low Correct power supply
Wrong rotation
direction
Wrong sequence of phases Reverse connections at motor or at switchboard
Motor overheats
while running
Overload Reduce load
Frame or ventilation openings
may be full of dirt and prevent
proper ventilation of motor
Open vent holes and check for a continuous stream of air from the motor
Motor may have one phase open Check to make sure that all leads are well connected
Grounded coil Motor must be rewound
Unbalanced terminal voltage Check for faulty leads, connections and transformers
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