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Installation and maintenance - Three-phase induction motors
4850 en - 2018.11 / f
PREVENTIVE MAINTENANCE
3.2 - Bearing maintenance
3.2.1 - Checking the bearings
As soon as you detect any of the following on the motor:
- Abnormal noise or vibration
- Abnormal temperature rise in the bearing even though it has
been lubricated correctly,
the condition of the bearings must be checked.
Damaged bearings must be replaced as soon as possible
to prevent worse damage to the motor and the equipment
being driven.
If one bearing needs to be replaced,
the other bearing must
also be replaced
.
The seals should be changed routinely
when the bearings
are changed.
The free bearing must allow the rotor shaft to expand (check its
identification during dismantling)
.
3.2.2 - Reconditioning the bearings
Bearings without grease nipples
Dismantle the motor (see section 6.1); remove the old grease
and clean the bearings and accessories with degreasing
agent.
Fill with new grease: the correct amount of new grease for the
bearing is 50% of the free space.
Bearings with grease nipples
Always begin by cleaning the waste grease channel
If using the type of grease stated on the nameplate, remove the
covers and clean the grease nipple heads.
If a different grease from that on the nameplate is being used,
the motor must be dismantled and the bearings and accessories
cleaned with degreasing agent (carefully clean the grease inlet
and outlet pipes) to remove the old grease before relubrication.
To ensure correct lubrication, fill the inner free spaces of the
bearing retainers, flanges and grease pipes and 30% of the
bearing free space.
Then rotate the motor shaft to distribute the grease.
Warning:
Too much grease causes the bearing to overheat (statistics
show that more bearings are damaged through too much
grease than too little grease).
Important note:
The new grease should be recently manufactured, of equivalent
performance and should not contain any impurities (dust,
water, etc).
4 - PREVENTIVE MAINTENANCE
Please consult LEROY-SOMER who, in its continuous search
for ways to help customers, has evaluated numerous methods
of preventive maintenance.
The diagram and table below give the recommended
equipment to use and the ideal positions to take measurements
of all parameters which can affect the operation of the machine,
such as eccentricity, vibration, state of bearings, structural
problems, electrical problems, etc.
M 01V
M 02V
M 02A
M 02H
M 01H
1
3
4
2
5
Detector
Measurement
Measurement points
M 01V M 01H M 02V M 02H M 02A Shaft E01 E02 E03
Accelerometer
For measuring vibrations
• • • • •
Photo-electric cell
For measuring speed and phase
(balancing)
•
Clamp ammeter
For measuring current
(D.C. and 3-phase)
• • •
Voltage probe
For measuring voltage
• • •
Infra-red probe
For measuring temperature
•
•
