Alternator Testing - Westerbeke 8.0KW-60Hz Service Manual

ALTERNATORS TESTINGJTROUBLESHOOTING
DESCRIPTION·
50 AMP MITSUBISHI
ALTERNATOR
REFER TO THE WIRING
: OIAGRAM IN THIS
MANUAL FOR ALL
WIRING CONNECTIONS
The following infonnation applies to the stal)dard alternators
that are supplied with WESTERBEKE'S Engines and
Generators.
ELECTRICAL CHARGING CIRCUIT
The charging system consists of an alternator with a voltage
regulator, an engine DC wiring harness, a mounted DC
circuit breaker and a battery with connecting cables. Because
of the use
of
integrated circuits (IC's), the electronic voltage
regulator is very compact and is mounted interna1ly or on the
back of the alternator.
It
is desirable to test the charging system (alternator and
voltage regulator) using the wiring hamess and electrlcal
loads that are a pennanent 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
electrlcal system. .
ALTERNATOR DESCRIPTION
The stator is connected to a three-phase, full-wave bridge
rectifier package which contains six diodes. The bridge
converts the AC generated in the stator to a DC output for
battery charging and accessories,
Power to the regulator and the field of the integral regulator
alternator is provided by the field diode (or diode trlo)
package contained in the alternator.
These alternators produce a rated output of 50 or 51 amps.
rated output is achieved at approximately 6000 alternator
rpm at an ambient temperature of 75°F (23.8°C). The .
alternators are desigued to operate in an ambient temperature
range of -40° to 212"F (-40° to 100°C).
VOLTAGE REGULATOR
The integral voltage regulator is an e1ectronic 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 regulator desigu utilizes all-silicou semi conductors and
thick-film assembly techniques. After the voltage has been
adjusted to the proper regulating valve, the 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 detenuine if a problem
exists with the charging circuit or with the alternator. If it is
detenuined that the alternator or voltage regulator is faulty,
have a qualified technician check it.
A
WARNING:
A working alternator
run~
hot. A failed
alternator can become very hot. Do not touch the
alternator until
If
has cooled.
LOW BATTERY/FAULTY CIRCUIT
If the starter only moans or makes a clicking sound instead
of spinniug 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 alternator and voltage regulator,
testing the following checks are recommended. •
1. Make certain 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
tenuinals, connectors and plugs are clean
and tight. Loose or corroded connections cause high
resistance and this could cause overcharging,
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.
Engines & Generators
54