Westerbeke 5.0KW BCG-60Hz Service Manual page 70

BC GENERATORS 5.0n.O KW
DESCRIPTION
The BC generator is a brushless, self-excited generator which
requires only the driving force of the engine to produce an
AC output. The stator houses two sets of windings; the main
stator windings and the exciter windings. When the generator
is started, residual magnetism in the four rotating poles
induces a voltage in the stator which then generates an even
larger voltage in the exciter windings. This mutual build up
of voltage in the four rotating poles and in the exciter wind-
ings quickly reaches the saturation point of the capacitor(s)
and a regulated energy field is then maintained in the stator.
At the same time, this regulated field produces a steady volt-
age in the stator windings which can then be drawn off the
generator's AC terminals to operate AC equipment. The
generator is a single-phase, reconnectable 120 volt AC
two-wire or 115 volt AC two-wire or 230 volt AC two-wire,
at 50 hertz.
Winding Connections: The single-phase synchronous
generator has 4 stator leads and can be configured to
120 volt output.
Bearings: The bearings are sealed type and permanently
greased requiring no maintenance during their working life
(approx. 30,000 hours).
PRELIMINARY CHECKING
Before electrical testing, check for proper engine speed/hertz
adjustment. Low engine speed will cause low AC voltage
output, high engine speed-high AC output.
Refer to
WESTERBEKE'S
operators manual or service man-
ual for engine speed/hertz adjustment or for other possible
engine related problems.
Before testing, get a clear explanation of the problem that
exists, be certain it relates to generator components.
A
WARNING:
AC and DC circuits often share tlie
same distributor panel. Be certain to unplug AC power
cords and shut down DC/AC inverters. Simply switching
off circuit breakers will not do the job since It will still
leave hot wires on the supply side of the panel.
INTRODUCTION TO TROUBLESHOOTING
The following test procedures can be used to troubleshoot
WESTERBEKE'S
4
POLE DUAL EXCITER CIRCUIT
BRUSHLESS GENERATORS.
Due to the simplicity of the
generator, troubleshooting is relatively easy.
Field testing and repairing can be accomplished with basis
tools and repair parts which should include the following:
A quality multimeter (multitester) capable of reading less
than one ohm and with a specific diode testing function.
Basic electrical tools including cutters, soldering iron, wire
strapper/crimper, terminal connectors, etc.
Repair parts such as diodes, fuses, bridge rectifier, etc.
A
CAUTION: (ON SOLDERING)
When soldering,
use
a
large enough soldering iron to get the job done
quickly. Excessive heat will damage the diodes. Also
make certain nD soldering splashes Dnto the windings
as It will melt the insulation.
ROTATING FIELD/AUXILIARY WINDINGS
WINDINGS WINDINGS
Two sets of windings are found in the rotor assembly. An AC
voltage is produced in two groups of windings as the rotor
turns
at its rated rpm. This AC voltage passes through each
of the two diodes mounted on the isolated fixture just before
the rotor carrier bearing. The AC sine wave is changed to DC
and this DC voltage is passed through the two groups of
rotating field windings producing a DC field around these
windings. This field affects the AC winding of the two main
stator groups inducing an AC voltage in these windings that
is available at the AC terminal block connections.
Engines & Generators
62