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D.
Generator
The 400-Hz
generator
is a brushless,
revolving
field,
three-phase,
alternating
cur-
rent type .' The rotor assembly ,is mounted
by two,
permanently
Lubricated,
sealed,
balj
bearings.
The, front bearivg
is supported
by the fan housing;
the- rear bearing
is mounted
in the exciter
housing.
Both of these housings are attached
to.the,main
generator
stator housing.
The front end of the rotor shaft extends
forward beyond
- the bearing
and is attached
to the engine
flywheel
by a hub and flexible
disc
dougling
atiembly.
The rear end of the rotor shaft extends
rearward
beyond
the
rear bearing
and into the exciter
stator housing.
The exciter
rotor is mounted
on
' thjs shaft extension
with
a Woodruff
key and is secured
by a washer and l/2"-13
thd,
cap screw.
A rectifier
hith'six
diodes
is mounted
on the exciter
rotor and
converts
exciter
AC output
to DC for excitation
of the generator
revolving
fields.
The exciter
DC output..to
the generator
fields,
and consequently
the generator
output,
is controlled
by the amount of DC voltage
supplied
to exciter
fields by
the static
voltage
regulator.
A centrifugal,
radial-blade
fan which
is part
of the hub and coupling
assembly,
draws cooling
air over all
internal
windings.
Air enters at the exciter
end and 'is discharged
at the drive
end.
The complete
generator
is bolted
to the engine
flywheel
.housing.
E.
Control
Box Assembly
The control
box (Fig.
6)
is a sheet.metal
enclosure
which
houses and provides
mounting
facilities
for generator
and engine
controls
and monitoring
equipment.
The box is equipped
with
two,
drawer
type trays which
contain
generator
output
control
devices
and monitoring
instruments.
Trays slide
in and out on nylon roller!
5
for easy access to internally
mounted
components.
Each tray is easily
*movable
by ;d isconnecting
an "Amphenol"
connector,
unlocking
safety
latches,
and sliding
the complete
tray assembly &t-of
the control
box.
A
shielded,
instrument
panel
I ight
is
mounted
on the left side of the control
box front panel,
to illuminate
controls
and instruments
in the trays.
(1)
Generator
control
tray (See Figure
7)
The generator
control
tray contains
instruments
and controls
for monitoring
and controlling
the generator
output.
(a)
Resistors
Two,
25-ohm,
loo-watt,
ballast
resistors
(2) are connected
in seiies
in the generator
exciter
DC field
circuit.
I 1
A variable
resistor
(1)
is connected
in series between
the manual
contra
rectifier
(14) and rheostat
(13).
Its purpose
is to !adiust the DC voltage
to the rheostat
and thus deteimitie
the vbltage
range through
which. the
rheastat
con control
generator
output voltage..
.
I
July
ln6
l-1
Page 13
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