Case 580SR Service Manual page 972

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6. ALTERNATOR
6.1 SPECIFICATIONS
Manufacturer .............................................................................................................................................Denso
Rated voltage ...............................................................................................................................................12 V
Polarity .................................................................................................................... Negative terminal grounded
Current ........................................................................................................................................................90 A
Minimum charging speed ..................................................................................................................... 1400 rpm
Maximum speed................................................................................................................................... 9000 rpm
Operating temperature ................................................................................................................ -30 °C to 90 °C
Direction of rotation .................................................................................... Clockwise seen from the pulley side
Regulated voltage at 5000 rpm with 10 A at 25 °C .........................................................................14.2 - 14.8 V
Maximum load that can be applied at terminal L.........................................................................12 V, 3.4 W x 6
6.2 DESCRIPTION AND OPERATION
The alternator, installed on the motor, on the front
RH side of the vehicle, is driven by the crankshaft
pulley with the help of a belt. The alternator contains
built-in regulators.
Current draw of the starter motor circuit:
When the ignition key is turned, a current of low in-
tensity is sent by the battery to the field winding of
the rotor (terminal IG).
At this stage, the indicator lamp (terminal L) turns on
and the rotor is partially magnetized.
When the motor starts and the partially magnetized
rotor rotates inside the stator, a three-phase alter-
nating current is generated (terminal B+). A constant
portion of this current is transformed into a direct cur-
rent by three excitation diodes installed in the rectifi-
er.
The direct current is sent as reinforcement through
the field winding of the rotor.
Using this method an increase in the magnetic field
of the rotor is obtained, as well as a rapid rise in the
voltage and current generated at the output.
The luminosity of the indicator lamp decreases when
the voltage generated at the output is increasing (ter-
minal L). The indicator lamp goes out when the volt-
age at terminal "L" is equal to that of the battery.
The voltage continues to increase up to the value
predefined by the regulator.
In case the alternator belt is broken, the voltage does
not accumulate in the alternator and the load indica-
tor lamp remains lighted to indicate the problem.
SECTION 55 - ELECTRICAL SYSTEM
1. Ground connection
2. Terminal P: motor tachometer
3. Terminal L: charge indicator
4. Terminal B+: charge +12 V
5. Terminal IG: +12 V after ignition (10 A fuse)
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