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BT GENERATOR
This generator is a brushless self-excited generator, which requires
only the driving force of the engine to produce AC output.
Two perma-
nent
magnets
in
the
exciter
stator
are
responsible
for
the
self-
exciting feature of this generator.
The magnetic field they produce
causes an AC voltage to be induced into the related exciter rotor win-
dings during rotation.
Diodes located in the exciter rotor rectify
this
voltage to DC and supply
it
to
the
windings
of the
rotating
field.
This creates an electromagnetic field which rotates through
the
windings
of
the
main
stator,
inducing
an AC voltage which
is
supplied to a load.
A transformer is connected in parallel to the AC
output of the main stator.
An AC voltage is produced in the auxiliary
windings of the transformer and main stator and is, in turn, supplied
to a full-wave bridge rectifier.
The rectifier produces a DC voltage
to further excite the exciter stator windings, enabling the generator
to produce a rated AC output.
An optional solid-state voltage regulator is available to work in tan-
dem with the transformer regulator to produce a more stable AC output.
No-Load Voltage Adjustment
Voltage adjustment
is
made
with
the compound tr ansformer
governing
generator regulation.
1.
The selector switch must be in the COMP position.
2.
Operate
the
generator
and
apply
a
moderate
load
momentarily;
then remove the load.
Note the voltage output from the genera-
tor's 120-Volt leg (s)
(110 Volts at 50 Hertz).
The no-load volt-
age
should
be
between
121
123
Volts
at
61.5
62
Hertz
(Ill - 113 Volts at 51.5 - 52 Hertz).
NOTE:
The no-load voltage should be adjusted to the voltage
produced by the generator when:
the generator is started, a
momentary load is applied to excite the transformer, and then
removed.
The voltage produced by the generator after this
momentary load is removed is the no-load voltage.
3.
To raise or lower the voltage, shims of varying thickness
(non-
conductive material) are inserted or removed from under the lami-
nated steel bar on top of the compound transformer.
The material
used for
shimming should not soften at temperatures in the 80·C
range.
A small reduction in no-load voltage (1 to 3 Volts) some-
times can be accomplished by gently tapping the top of the lami-
nated steel bar to reduce the air gap between the existing shims
and the transformer core.
18
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