WEG S Series - Page 52

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52 l Installation, Operation and Maintenance Manual – Synchronous Motors – S Line – Brushless – Horizontal 11866576
ABNORMALITY POSSIBLE CAUSES CORRECTION
Hot spots in the rotor
 Interruptions or failure in the insulation of the
rotor winding
 Repair the rotor winding
 Motor overexcited  Check and correct the exciting current
Heating in the damper winding
(rotor)
 High negative sequence current
 Correct voltage unbalance;
 Check the line harmonics (correct)
Abnormal noise during
operation with load
 Mechanical causes: The noise normally
decreases when the speed reduces; see also:
“noisy operation when uncoupled”
 Check mechanical causes (balancing,
alignment, coupling, bearings...)
 Electrical causes: The noise disappears when
the motor is shut down. Consult the
manufacturer
 Perform electrical and magnetic analysis
When coupled, there is noise;
when uncoupled, the noise
disappears
 Defect in the coupling parts or in the driven
machine
 Check the power transmission, the
coupling and the alignment
 Defect in the gear coupling
 Align the driving set, check the gear box
position
 Defect in the coupling  Align the motor and the driven machine
 Problems in the foundation  Repair the foundation
 Faulty balancing of the components or of the
driven machine
 Perform new balancing
 Power supply voltage is too high
 Check the supply voltage and the
current with no load
 Wrong rotation direction of the motor  Invert the connection of two phases
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 at 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
 Correct or replace the shaft
 Check the rotor balancing and
eccentricity
 Air-gap is not even
 Check shaft warping or rolling bearing
wear