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11239449 Installation, operation and maintenance manual – Squirrel cage motor – W Line - Horizontal and vertical l 51
ABNORMALITY POSSIBLE CAUSES CORRECTION
Stator winding becomes very
hot under load

Insufficient cooling due to dirty water
channels

Clean the water 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

Voltage too low, therefore, the current is
very high

Check the supply voltage and the voltage
drop on 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

Check the air-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

Unbalance in the power supply (blown fuse,
wrong command)

Check if there is voltage unbalance or
operation with two phases and correct it

Dirty windings

Clean the windings

Rotation direction is not compatible with the
used fan

Check the fan regarding to the motor
rotation direction
Noisy operation when
uncoupled

Unbalance

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 deformed

Check flatness of the base

Bent shaft

Check the rotor balancing and eccentricity

Air-gap is not even

Check shaft warping or rolling bearing wear