4.2.2 TWO BEARING GENERATORS A flexible coupling should be fitted and aligned in accordance
with the coupling manufacturer's instruction. If a close
coupling adaptor is used the alignment of machined faces
must be checked by offering the generator up to the engine.
Shim the generator feet if necessary. Ensure adaptor guards
are fitted after generator/engine assembly is complete. Open
coupled sets require a suitable guard, to be provided by the
set builder. In the case of belt driven generators, ensure
alignment of drive and driven pulleys to avoid axial load on
the bearings. Screw type tensioning devices are
recommended to allow accurate adjustment of belt tension
whilst maintaining pully alignment. Side loads should not
exceed values given in SECTION 3. Belt and pulley guards
must be provided by the set builder.
Important ! Incorrect belt tensioning will result in
excessive bearing wear.
Incorrect guarding and/or generator
alignment can result in personal injury
and/or equipment damage.
4.2.3 SINGLE BEARING GENERATORS
Alignment of single bearing generators is critical. If necessary
shim the generator feet to ensure alignment of the machined
surfaces.
For transit and storage purposes the generator frame spigot
and rotor coupling plates have been coated with a rust
preventative.
This MUST BE removed before assembly to engine.
A practical method for removal of this coating is to clean the
mating surface areas with a de-greasing agent based on a
petroleum solvent.
Care should be taken not to allow any
cleaning agent to come into prolonged
contact with skin.
The sequence of assembly to the engine should generally be
as follows:
1. On the engine check the distance from the coupling
mating face on the flywheel to the flywheel housing
mating face. This should be within +/-0.5mm of nominal
dimension. This is necessary to ensure that a thrust is not
applied to the a.c. generator bearing or engine bearing.
1. Check that the bolts securing the flexible plates to the
coupling hub are tight and locked into position. Torque
tightening is 24.9kgfm (244Nm; 180 lb ft).
2a. UCD224 Only
Torque tightening is 15.29 kgfm (150Nm; 110 lb ft).
1. Remove covers from the drive end of the generator to
gain access to coupling and adaptor bolts.
1. Check that coupling discs are concentric with adaptor
spigot. This can be adjusted by the use of tapered
wooden wedges between the fan and adaptor.
Alternatively the rotor can be suspended by means of a
rope sling through the adaptor opening.
1. Offer the a.c. generator to engine and engage both
coupling discs and housing spigots at the same time,
finally pulling home by using the housing and coupling
bolts. Use heavy gauge washers between bolt head and
discs on disc to flywheel bolts.
1. Tighten coupling disc to flywheel. Refer to engine ma nual
for torque setting of disc to flywheel bolts.
1. Remove wooden wedges.
Incorrect guarding and/or generator
alignment can result in personal injury
and/or equipment damage.
The generator frame should be solidly bonded to the
generating set bedplate. If antivibration mounts are fitted
between the generator frame and its bedplate a suitably rated
earth conductor (normally one half of the cross sectional area
of the main line cables) should bridge across the antivibration
mount.
Refer to local regulations to ensure that
the correct earthing procedure has been
followed.
4.4 PRE-RUNNING CHECKS 4.4.1 INSULATION CHECK Before starting the generating set, both after completing
assembly and after installation of the set, test the insulation
resistance of windings. The AVR should be disconnected
during this test. A 500V Megger or similar instrument should
be used. Disconnect any earthing conductor connected
between neutral and earth and megger an output lead
terminal U, V or W to earth. The insulation resistance reading
should be in excess of 5MΩ to earth. Should the insulation
resistance be less than 5MΩ the winding must be dried out as
detailed in the Service and Maintenance section of this
Manual.
Important ! The windings have been H.V. tested during
manufacture and further H.V. testing may
degrade the insulation with consequent
reduction in operating life. Should it be
necessary to demonstrate H.V. testing, for
customer acceptance, the tests must be
carried out at reduced voltage levels i.e.
Test Voltage= 0.8 (2 X Rated Voltage + 1000)
Caution !
Caution !
Caution !
Warnin
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