Nidec 22765-01, Manual

Page: 193 / 227

Page 22
Foot Deflection
After alignment, check for foot deflection or “soft foot” condition
on each shim location to eliminate distortion of the generator
frame. Do this by loosing one mounting bolt at a time and checking
deflection after retightening. Deflection at the shim location from
shims under compression to a loosened condition must not exceed
0.003" (0.0762 mm).
Doweling
In case the mounting bolts loosen during operation, doweling will
prevent movement of the generator. Dowel as follows:
Check the alignment after the generator has been in operation for at
least 48 hours. If alignment is not satisfactory, realign.
Drill holes through the footpads and into the base in two mounting
pads opposite each other. Drill the holes slightly smaller than the dowel
pin.
Ream the holes to the proper diameter for the pin. Clean out chips, and
install the pins.
Electrical Connections
If the generator was subjected to a rapid change in temperature,
freezing or wet conditions during shipment or storage, measure
the insulation resistance of each winding and dry the generator, if
necessary, as described in the maintenance section below.
Make all electrical connections (main load, temperature monitoring
device, space heater, AVR) in accordance with local regulations and
national/international electrical code requirements. Check the electrical
diagrams provided with the generator or manual. The main terminals
need to be properly spaced for the load connections. Refer to Tables 5
and 6 for the proper torque values for the connections.
On larger generators grounding points are provided for properly
grounding the system to the generator frame. The grounding wire must
be sized to national/international code requirements.
Space Heaters
When the generator has optional space heaters to prevent water
condensation during long periods of downtime, connect the space
heaters so they start when the generator is turned off and stop when
the generator is switched on. Some generators with space heaters have
thermostats. The thermostat should be set above the dew point. Refer
to the electrical diagrams for the space heater characteristics.
CAUTION: The space heaters
are designed to be energized when the
generator is shut down. They are hot
enough to cause skin burns. Terminals for
power at the space heaters are live during
operation. Disconnect power to the space
heaters before removing the generator
covers.
NOTE: Alternator current machines are
intended to for continuous operation
with the neutral or at near ground
potential. Operating with one line at
ground potential should be done only
for infrequent periods of short duration,
for example as required for normal fault
clearance.