Rotor Turning; Coupling; Alternators With Double Bearing (B35T / B3T); Direct Coupling - WEG G Serie Manual De Instalación, Operación Y Mantenimiento

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4.9.2.3

Rotor turning

ATTENTION
It should not be used alternator fan to rotate
the shaft, because this might result in
damage to the alternator and / or personal
injury, especially when the alternator is
coupled with the driven machine.
Figure 4.10: Rotor turning
4.9.3

Coupling

4.9.3.1 Alternators with double bearing (B35T /
B3T)

4.9.3.1.1 Direct coupling

Direct coupling is always preferable the due to lower
cost, less space, no slip (belt) and greater security
against accidents. In case of transmission with respect
to speed, it is also common for direct coupling with a
gearbox.
ATTENTION
Carefully align the shaft ends, using a flexible
coupling whenever possible, leaving
minimum clearance of 3 mm between the
couplings.
Figure 4.11: Axial clearance

4.9.3.1.2 Coupling by pulleys and belts

When a speed ratio is required, the transmission belt is
the most frequently used.
Avoid unnecessary radial efforts on the bearings, locating
the shafts parallel to each other and pulleys perfectly
aligned.
Belts that work laterally biased transmit alternating
knocks to the rotor, and may damage the backs of the
bearing. The slip of the belt can be avoided by applying a
resinous material such as pitch, for example.
Belt tension should be just sufficient to prevent slipping
during operation.
34 l Installation, operation and maintenance manual – Synchronous Alternator – G line - Horizontal
Axial clearance
NOTE
Excessive tension in the belt increases stress
on the shaft, causing vibration and fatigue
and may even reach the fracture of the shaft.
The use of too small pulleys must be avoided; these
cause bending of the alternator shaft due to the fact that
the traction in the belt increases as the diameter of the
pulley decreases.
ATTENTION
The double bearing alternators are made for
applications with direct coupling.
In applications with the use of pulleys and
belts, WEG should be consulted to ensure a
correct application of the alternator.
NOTE
Always use properly balanced pulleys. Avoid
scraps of keys, as they represent an increase
of the mass of unbalance. If these
observations are not followed, there will be
increased levels of vibration.

4.9.3.2 Alternator with single bearing (B15T)

4.9.3.2.1 Measure "G"

The alternators leave the factory mounted with discs and
flanges according to customer request. Measure G is the
distance between the outer face of the discs in relation to
the flange face, as shown in Figure 4.12:
NOTE
The alternators leave the factory with the
measure "G" as shown in Table 4.10.
It is up to the assembler of the alternator set
the responsibility of verifying that the
measure "G" is consistent with the diesel
engine used. If measure "G" is not
respected, this may result in serious damage
to the alternator and the diesel engine or, in
some cases it will not be possible to attach
the alternator to the engine diesel.
Coupling Disc
Figure 4.12: G dimension
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