positive
(B+)
to ensure adequate residual magnetism to
voltage build-up. As the engine starts and speed
increases, the rotating field induces avoltage build-up in
the
stator windings.
A
portion of
the
AC
current gener-
ated in the stator windings
is
rectified
to
DC
by
the
CR4
bridge rectifier. The
DC
current is supplied to the rotating
field windings to create the strong magnetic field
required for generating the rated current.The ACvoltage
build-up stabilizes at approximately
128
volts when the
engine reaches governed speed.
To
prevent an excessive voltage drop when a load is
applied to the generator, a method for regulating the AC
output voltage is required. The voltage regulating trans-
former allows the generator to provide a stable AC out-
put voltage under varying load conditions. Each trans-
former primary winding
(Hl-H2
and
H3-H4)
is con-
nected in series with one of the stator AC output
windings. The full AC output current produced by the
generator flows through these two primary windings.
Increasing or decreasing the current output from the
transformer winding produces a corresponding increase
or decrease in the primary current produced in the
secondary winding. The secondary winding is con-
nected in series with the circuit that supplies AC current
for rectification to DC field current.
During operation, adding load increases the current flow
through the transformer primary windings which causes
a corresponding increase in the current output from the
transformer secondary winding. This
boosts
the
DC
field current to a higher level to offset the voltage
drop that would normally occur when a load is
applied.
In
the
same
manner, decreasing the
load
reduces the
DC
field current to offset the voltage rise
that would normally occur when a load is removed.
Continuously adjusting the field current as the load
changes is how voltage regulaton is achieved.
GENERATOR TROUBLESHOOTING
Use the following troubleshooting guide to help locate
problems related to the generator. Figures
8-1
and
8-2
show the location of most of the generator components.
Refer to the wiring diagram in Figure
8-4
for the location
of all terminal connections. The troubleshooting guide
is
divided into four sections. After identifying the problem,
refer to the guide for the possible cause and the recom-
mended corrective action.
STATOR
HOUSING
LOAD(8LACKl.
10
CB
NEUlRlLl
WHITE1.m
lRAHSFM1YER GND
GNOIGREENI. TO
TRANSFORMER GND
ES-1557
FIGURE
8-2.
VOLTAGE REGULATING TRANSFORMER
8-3
Redistribution or publication of this document
by any means, is strictly prohibited.
Redistribution or publication of this document
by any means, is strictly prohibited.
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