Maintenance; Cleaning; Complete Checkup; Bearing Change - WEG G truck Serie Manual De Instalación, Operación Y Mantenimiento

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8 MAINTENANCE

In alternator maintenance, when properly applied, insulation levels should be periodically inspected, temperature rise (windings
and bearings), wears, bearing lubrication and bearing life, occasional checking of fan, for proper airflow, vibration levels.
Failure to comply with one of the recommendations provided above may result in unexpected equipment downtime. The
frequency with which such inspections are performed depends on local application conditions.
In case the generators are used in emergency supply groups, they must receive load 2 to 3 hours a month, depending on the
humidity level of the installation location.

8.1 CLEANING

The terminals in the terminal box must be clean, free of
rust, in perfect mechanical condition and without deposits
of grease or verdigris.
The alternator noise must be observed at regular intervals
of 1 to 4 months. A well trained ear is perfectly capable of
distinguishing unusual noises in the bearings, even with
rudimentary tools (a screwdriver, etc.).
For a more reliable analysis of the bearings, it is advisable
to use equipment that allow making predictive analytics.
The temperature control of the bearing is also part of the
routine maintenance. The temperature rise must not
exceed 60 °C, measured on the bearing external ring.
The temperature may be constantly controlled by
thermometers placed outside the bearing, or with
embedded thermo-elements.

8.2 COMPLETE CHECKUP

Clean the dirty windings with a brush. Use a cloth
moistened in alcohol or suitable solvent to remove grease,
oil and other impurities from the winding. Dry with dry air.
Blow compressed air through the ventilation channels
on the lamination core of the stator, rotor and bearings.
Drain the condensed water and clean the inside of the
terminal boxes and slip rings.
Measure the insulation resistance or the polarization
index, as item 2.3.2 of this manual.

8.3 BEARING CHANGE

You should not remove a shaft bearing unless it is
absolutely necessary.
First remove the external bearing rings of bearings and
removing the covers. The complete rotor must be removed
from the stator carefully toward the DE.
To withdraw the bearings must be used an extractor with
3 claws to support the inner ring.
Before the installation of the new bearings (as specified),
the shaft seats must be cleaned and slightly lubricated.
The bearing to be mounted must be preheated
(+/-80 ºC), taking care so that they are embedded in
perfectly centered position relative to the shaft.
The bearings must not be subjected to knocks or shocks
or not safe stockpiles where there is humidity and
vibration, because these may create marks on the races
causing noisy operation and rapid wear of bearings.
20 l 10258257 - Installation, Operation and Maintenance Manual

8.4 ROTATING DIODE CHANGE

When damage to one of the rotating diodes occurs, it is
also necessary to check the characteristics of passage or
blockage of other diodes. The diode set is part of the field
excitation circuit of the synchronous machine.
To check whether there is or not damage the diodes,
simply remove the shutter attached to the back cover and
make the necessary measurements. To replace a diode it
is necessary to remove the back cover (by unscrewing the
frame and disconnecting the cables coming out of the
exciter stator and are connected to the voltage regulator).
The diode clutch has the following electrical configuration:
Rotor of main
exciter
Diode set (rectifier BRIDGE)
Figure 8.1: Field excitation circuit
NOTE
We will use the following conventions:
AND – frame anode; (+)
CTD – frame cathode. (-)
Rotor (field) of
main machine