Mitsubishi Heavy Industries L2 Service Manual page 131

ALTERNATOR AND DYNAMO
Field coil
Figure 134 Dynamo
Alternator
Key switch
Figure 135 Checking for regulated voltage
130 / 155
Magnet
Ammeter
Battery
33.2 Dynamo
The dynamo is used for specific engines. This
maintenance-free dynamo is the permanent magnet
type, light-weight, compact, single-phase AC generator.
Alternating current generated by the dynamo is rectified
through the separated regulator-and-rectifier unit.
33.3 Inspection of the alternator
(installed on the engine)
CAUTION
Improper handling will damage to the charging circuit
and other troubles.
1. Never connect the battery in reverse.
2. Do not use a megger and other high-voltage
testers.
3. When recharging the battery, disconnect the
battery cable from the alternator.
4. Never disconnect the lead wire from the
alternator terminal B during running of the
engine.
5. Never ground the alternator terminal B, since this
terminal is always charged.
6. Never short-circuit or ground terminal L.
7. When using a steam cleaner, be careful not to
direct steam to the alternator.
33.3.1 Inspection for regulated voltage
1. Connect an ammeter between positive terminal of
battery and terminal B of alternator.
2. Connect a voltmeter to the alternator terminal "L"
and ground.
3. Note that the voltmeter indicates zero volt when
the key switch is in the OFF position. The
voltmeter will indicate a voltage considerably lower
than battery voltage when the key switch is in the
ON position (while the engine stops).
4. Short-circuit the ammeter terminals to start the
engine.
5. Read the voltmeter indication (regulated voltage)
under the following test conditions: Ammeter
indication is below 5 A; engine speed is at 1800
rpm and 2500 rpm; and lamps are switched off.
Regulated voltage shows a tendency to decrease
as the alternator temperature increases.
ENGLISH
ELECTRICAL SYSTEM
Service Manual Mitsubishi L-Series diesel engines
Version 08/2004