Bt Generator - Westerbeke 15.0BTD60-HERTZ Operator's Manual

BT GENERATOR
This generator is a four-pole, brushless, self-excited generator which requires only the driving force of the
engine to produce AC output. The copper and laminated iron in the exciter stator are responsible for the
self-exciting feature of this generator. The magnetic field produced causes an AC voltage to be induced into
the related exciter rotor windings 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 wind-
ings of the transformer and main stator and is, in tum, 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 tandem with the transformer regulator to
produce a more stable AC output (see the top of page 34).
No-Load Voltage Adjustment
Voltage adjustment is made with the compound transformer governing generator regulation.
1. The selector switch must be in the CaMP position.
2. Operate the generator and apply a moderate load momentarily; then remove the load. Note the voltage
output from the generator's 120-Volt leg(s) (110 Volts at 50 Hertz). The no-load voltage should be be-
tween 121 - 123 Volts at 61.5 - 62 Hertz (111 - 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, non-conductive shims of varying thickness are inserted or removed from
under the laminated steel bar that is situated on top of the compound transformer. The material used for
shimming should not soften at temperatures in the 176
0
F (80
0
C) range. A small reduction in no-load volt-
age (1 to 3 Volts) sometimes can be accomplished by gently tapping the top of the laminated steel bar to
reduce the air gap between the existing shims and the transformer core.
See the next page for an illustration
of
the generator's AC distribution box.
33