Defender 90 (LD) V8-4.0L (1997)
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Alternator: Description and Operation
Description and Operation
The generator is a 3 phase, field sensed unit. The rotor and stator windings produce three phase alternating current, AC, which is rectified to direct
current, DC. The electronic voltage regulator unit controls the generator output voltage by high frequency switching of the rotor field circuit. Use only
the correct auxiliary drive belt. Occasionally check that the engine and generator pulleys are accurately aligned.
It is essential that good electrical connections are maintained at all times. Of particular importance are those in the charging circuit (including those at
the battery) which should be occasionally inspected to see that they are clean and tight. In this way any significant increase in circuit resistance can be
prevented.
Do not disconnect battery cables while the engine is running or damage to the semi-conductor devices may occur. It is also inadvisable to break or
make any connections in the generator charging and control circuits while the engine is running.
The electronic voltage regulator employs micro-circuit techniques resulting in improved performance under difficult service conditions. The whole
assembly is encapsulated in silicone rubber and housed in an aluminium heat sink, ensuring complete protection against the adverse effects of
temperature, dust, and moisture etc.
The regulating voltage is set during manufacture to give the required regulating voltage range of 14.2 + 0.2 volts, and no adjustment is necessary. The
only maintenance needed is the occasional check on terminal connections and wiping with a clean dry cloth.
The generator system provides for direct connection of a charge (ignition) indicator warning light, and eliminates the need for a field switching relay
or warning light control unit. The lamp should be checked regularly. In the event of bulb failure, an 'exciter' voltage is supplied through a resistor,
wired in parallel to the bulb, ensuring that generator output is maintained.
When using rapid charge equipment to re-charge the battery, the battery MUST be disconnected from the vehicle.
