8
5.
Offer the AC 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 and head and discs on disc to flywheel bolts.
6.
Tighten coupling disc to flywheel bolts. Refer to
engine manual for torque setting of disc to flywheel
bolts.
7.
Remove wooden wedges.
8.
Replace covers. Check for excessive vibration at the
time of initial run-up.
Important!
Incorrect guarding and/or generator
alignment can result in personal injury
and/or equipment damage.
4.3 EARTHING
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.
4.4 PRE-RUNNING CHECKS
Caution!
Refer to local regulations to ensure that
the correct earthing procedure has been
followed.
4.4.1 INSULATION CHECKS
Before starting the generating set after completing assembly,
test the insulation resistance of the main stator windings.
It should be noted that as winding temperature increases
values of insulation resistance will significantly reduce.
Therefore true values of insulation resistance should be
established with windings at ambient temperatures.
Caution!
The AVR should be disconnected, and
the resistance temperature detector.
(RTD) leads grounded, during the test.
4.4.1.1 LV GENERATORS
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 5M
Ω
to earth. Should the insulation resistance be
less than 5M
Ω
the winding must be dried out as detailed in
the Service and Maintenance Section of this Manual.
4.4.1.2 MV GENERATORS
A 2500V motorised Megger or similar instrument should be
used. Separate the three neutral leads, ground V and W
leads and megger U to ground. Repeat for V phase with U
and W grounded and W phase with U and V grounded.
The insulation resistance should not be less than 50M
Ω
and
the polarisation index should be in the order of 2 or greater
at 20°C.
If these values cannot be achieved the winding should be
dried out as detailed in the Service and Maintenance section
of this manual.
Danger!
4.4.1.3 HV GENERATORS
A 5000 V motorised Megger or similar instrument should be
used. Separate the three neutral leads, ground V and W
leads and megger U to ground. Repeat for V phase with U
and W grounded and W phase with U and V grounded.
The insulation resistance should not be less than 200 M
Ω
and the polarisation index should be in the order of 2 or
greater at 20°C.
If these values cannot be achieved the winding should be
dried out as detailed in the Service and Maintenance section
of this manual.
Danger!
4.4.2 DIRECTION OF ROTATION
Standard machines are fitted with a backward inclined radial
bladed fan and therefore only suitable for running in one
direction of rotation. The generator is supplied to give a
phase sequence of U V W with the generator running
clockwise looking at the drive end (unless otherwise
specified at the time of ordering). If the generator phase
rotation has to be reversed after the generator has been
despatched apply to factory for appropriate wiring diagrams.
4.4.3 VOLTAGE AND FREQUENCY
Check that the voltage and frequency levels required for the
generating set application are within the range indicated on
the generator nameplate.
4.4.4 AVR SETTINGS
To adjust AVR settings remove the housing cover, and refer
to the label inside cover for guidance of adjustment
potentiometers and selection link location. The adjacent fig
1 also shows AVR layout.
Most of the AVR adjustments are factory set in positions
which will give satisfactory performance during initial running
tests. Subsequent adjustment may be required to achieve
optimum performance of the set under operating conditions.
Refer to section 4.7 for details.
Short stator terminals to earth
with an earthing rod after HV
testing, for at least 30 seconds
to discharge windings.
Short stator terminals to earth
with an earthing rod after HV
testing, for at least 30 seconds
to discharge windings.
