Westerbeke 7.6 kw EDT Operator's Manual page 41

ALTERNATORS TESTlNGJTROUBLESHOOTING
DESCRIPTION
, 50 AMP MITSUBISHI
• ALTERNATOR
CASE GROUND
REFER TO THE WIRING
DIAGRAM IN THIS
MANUAL FOR ALL
WIRING CONNECTIONS
The following information applies to the standard alternators
that are supplied with WES1ERBEKE'S Engines and
Generators.
ELECTRICAL CHARGING CIRCUIT
The charging system consists of an alternator with a voltage
regnlator, an engine DC wiring harness, a mounted DC
circuit breaker and a battery with connecting cables. Becanse
of the use of integrated circuits (lC's), the electronic voltage
regulator is very compact and is mounted internally or on the
back of the alternator.
It is desirable to test the charging systern (alternator and
voltage regulator) using the wiring harness and electrical
loads that are a permanent part of
the
system and will then
provide the technician with an operational test of the
charging system as well as the major components of the
electrical system.
ALTERNATOR DESCRIPTION
The stator is connected to a three-phase, full-wave bridge
rectifier package which contains six diodes. The bridge
converts fue AC generated in fue stator to a DC output for
battery charging and accessories,
Power to the regnlator and the field of the integral regnlator
altemator is provided by the field diode (or diode trio)
paCkage contained in the alternator.
These altemators produce a rated output of
50
or
51
amps.
rated output is achieved at approximately
6000
alternator
rpm at an ambient temperature of 75'P (23.8'C). The
altemators
are
designed to operate in an ambient temperature
nmge1lf<4<l'-t0-2l2'F-(,",O'-to·iOO'C);
VOLTAGE REGULATOR
The integral voltage regulator is an electronic switching
device which senses the system voltage level and switches
the voltage applied to the field in order to 'maintain a proper
system voltage.
The regnlator design utilizes all-silicon seini conductors and
thick-film assembly techniques. After the voltage has been
adjusted to the proper regnlating valve, fue entire circuit is
encapsulated to protect the circuit and the components from
possible damage due to handling or vibration.
ALTERNATOR TROUBLESHOOTING
Use this troubleshooting section to detennine if a problem
exists with fue charging circuit or with the alternator. If it is
detennined that the altemator or voltage regnlator is faulty,
have a qualified technician check it.
A
WARNING:
A working alternator runs hot. A failed
alternator can become very hot. 00 not ,touch the
alternator until if has cooled.
LOW BATTERY/fAULTY CIRCUIT
If the starter only moans or makes a cliCking sound instead
of spinning the engine to life it is likely a low battery or a
faulty connection in, the starting circuit and not an alternator
problem.
PRELIMINARY INSPECTION
Before starting
the
actual altemator and voltage regnlator,
testing the following checks are recommended.
1. Make certsin your alternator is securely mounted.
2. Check the drive belts for proper tension. Replace the belt
if it is worn or glazed.
3. Check that all tenninals, connectors and plugs are clean
and tight. Loose or COITa<;led connections cause high
resistance and this could cause overchai:ging,
undercharging or damage to the charging system. Badly
corroded battery cables could prevent the battery from
reaching a fully charged condition.
4. Check the condition of the battery and charge if necessary.
A low or discharged battery may cause false or misleading
readings in the tests.
NOTE: An isolator with a diode, a solenoid, or a battery
selector switch is usually mounted in the circuit to isolate
the batteries so the starting battery
is
not discharged along
with the house batteries.
If
the isolator is charging the
starting battery but not the hause battery, the alternator
is
OK and the problem
is
in the battery charging circuit.
~ WESTERBEKE
Engines
&
Generators
31