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11371757 Installation, operation and maintenance manual – Squirrel cage motor – M line – Vertical l 53
ABNORMALITY POSSIBLE CAUSES CORRECTION
Stator winding becomes
very hot under load
Fans with inverted rotation direction
Correct the rotation direction of the fans
Insufficient cooling due to dirty air channels
Open and clean the air passage channels
Overload
Measure the stator current; reduce the load.
Analyze the motor application
High number of starts or moment of inertia
too high
Reduce the number of starts
Voltage too high, therefore, the iron losses
increase
Do not exceed 110% of the rated voltage,
except when otherwise specified on the
nameplate
, therefore, the current is
high
Check the supply voltage and the voltage
drop in the motor
Interruption in a power cable or in a winding
phase
Measure the current in all the phases and, if
necessary, correct it
Rotor drags against the stator
gap, operating conditions
(vibration etc.), bearing conditions
The operating condition does not correspond
to the nameplate data
Keep the operating condition according to
the nameplate or reduce the load
wrong command)
Check if there is voltage unbalance or
operation with two phases and correct it
Dirty windings
Clean
Air ducts clogged
Dirty air filter
Clean the filter element
is not compatible with the
fan used
direction
Noisy operation when
uncoupled
Unbalance
Noise remains during deceleration after
disconnecting the voltage
Perform new balancing
Interruption in one phase of the stator
winding
Measure the current of all connecting cables
Fastening screws are loose
Retighten and lock the screws
The rotor balancing conditions become
worse after the assembly of the coupling
Balance the coupling
Resonance in the foundation
Adjust the foundation
Motor frame is deformed
Check flatness of the base
Bent shaft
The shaft may be warped
Check the rotor balancing and eccentricity
Air-gap is not even
Check the shaft warping or
wear
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