Komatsu 4D98 Series Shop Manual page 167

70. AIternator
(1)
(2)
(3)
(4)
Regulated voltage measurement
Open SW2 and close SW1 in the test circuit, and measure the voltage after raising the alterna-
tor speed to the rated speed (5,000 rpm).
The regulated voltage is normal if it is between 14.1 and 14.7 V.
rpm at 13.5 V
Open SW2 and close SW1 in the test circuit to gradually raise the alternator speed and measure
it when the voltmeter indicates 13.5 V.
It is the operating speed at 13.5 V.
The operating speed is normal if is 1,000 rpm or less.
Output current measurement
Set the variable resistor to the minimum position and close SW1 and SW2 in the test circuit to
obtain each alternator output speed. Adjust the variable resistor for a voltmeter reading of
13.5 V, and measure the current.
It is the output current.
Precaution for performance test
a) Use a lead with a sectional area of 8 mm* or more (thick lead) and 2.5 m or less in length for
each of connections between the alternator B terminal and battery positive terminal and
between E and battery negative terminal.
b) Use switches with small contact resistance in the test circuit.
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