Siemens 1SE0 Operating And Maintenance Manual page 17

Sr.
Trouble
No.
4 Motor starts sluggishly,
speed falls when load
is put on
5 Motor starts with
difficulty on star
connection or not at all
6 Stator heats up quickly
& takes large no load
current
7 Motor overheats while
running on load
8 Motor vibrates after
connections are made
9 Scraping noise
10 Magnetic noise
11 Shaft end breaks or
stator rotor rubbing
12 Heavy vibrations
13 Current unbalance
Cause
Rating not proper
Voltage too low at motor
terminals because of line
drop
Starting load torque too
high
Broken rotor bars
Load too high
Supply voltage low
Contacts burnt in star/delta
starter
Stator wrongly connected
Phase short
Multiple earth
Overload
One phase open
Shorted stator coil
Faulty connection
Motor operated on load
cycle not in accordance with
the name plate
High or low voltage
Foreign material in air gap
Rotor rubs stator bore
Motor misaligned
Weak foundation
Coupling out of balance
Driven equipment un-
balanced.
Balancing weights shifted.
Defective bearings
Bearings not in line
Excessive end play
Fan touching fan cover
Loose on bed plates
Airgap not uniform
Loose bearings
Excessive radial loads due to
pulley drives
Load unbalance
Unbalanced supply voltage
Remedy
Get correct type of motor.
- do -
Check load characteristics with motor
speed torque.
Look for cracks near the ring & if required
get new rotor.
Reduce load or use larger motor.
Check supply lines to motor.
Overhaul or replace starter.
Check connection.
Rewind
Rewind
Reduce load.
Check connections.
Repair & check wattmeter reading.
Correct the connections.
Run the motor on duty for which it is
specified.
Check voltmeter reading.
Dismantle & remove obstruction.
Recondition the rotor. Replace worn out
bearings.
Realign.
Provide strong base.
Balance coupling.
Re-balance.
Re-balance the rotor.
Replace bearings.
Line up properly.
Adjust bearings or add washers. Use
shims for alignment. Use vibration pads to
dampen external vibrations.
Remove interference.
Tighten mounting bolts.
Check & correct bearings.
Correct or replace bearings.
Check for suitability.
Re-balance.
Check voltage.
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