Checking Alternator Paralleling System; Alternator System Adjustments - Piper Navajo Chieftain PA-31-350 Service Manual

NAVAJO CHIEFTAIN SERVICE MANUAL
11-9. CHECKING ALTERNATOR PARALLELING SYSTEM. The alternator paralleling system
incorporates an ammeter which provides for an independent check of each alternator, as well as the
charge/discharge current of the battery. In the event either ALTERNATOR INOPERATIVE light begins to
glow or the ammeter check for either alternator fails to indicate an output, check the appropriate alternator
circuit breaker switch, also the voltage regulator circuit breaker. If the circuit breakers are in their normal
operating position, a further check of the alternator system should be accomplished. (Refer to Figure 11-4.)
a. Verify that the ammeters are indicating properly.
b. Disconnect the output (+) lead at the alternator.
c. Disconnect the field F-2 lead at the alternator.
CAUTION
DO NOT ALLOW THE FIELD LEAD TO COME IN CONTACT
WITH AIRFRAME GROUND WHEN THE MASTER SWITCH IS
ON AS THE VOLTAGE REGULATOR WILL BE DAMAGED.
d. Verify that all electrical units are off and the battery is fully charged.
e.
Turn on the appropriate section of the master switch for the alternator being tested. (L or R.)
f.
To check the alternator output circuit, connect a voltmeter or 24 volt test light to the previously
disconnected output (+) lead. Check that the circuit breaker switch for the alternator under test is turned
on. If a reading of approximately 24 volts is obtained on the voltmeter, or the test light glows, the output
circuit is operational.
g.
Should there be no indication of voltage, trace back through the output circuit until voltage is
indicated. (Refer to Figure 11-4.) A component that does not indicate voltage at both its input and output
terminals should be replaced.
h. Check the field circuit by connecting a voltmeter to the previously disconnected field (F-2) lead.
If a reading of approximately I to 3 volts is obtained the field circuit is operative.
i. If voltage is present at both the output and field leads, the alternator should be checked for a
possible malfunction. (Refer to paragraph 11-11.)
11-10. ADJUSTMENTS. The only adjustment necessary to maintain the alternator system is the
adjustment of the voltage control on the voltage regulator. A voltage of 28.5 volts is maintained. All other
control adjustments are made at time of installation and need not be reset.
IMPORTANT
Since the alternator and regulator are designed for use on only one
polarity system, the following precautions must be observed when
working on the charging circuit. Failure to observe these
precautions will result in serious damage to the electrical
equipment.
a. When installing a battery, always make absolutely sure
the ground polarity of the battery and the ground
polarity of the alternator are the same.
b.
When connecting a booster battery, make certain to
connect the negative battery terminals together and the
positive battery terminals together.
c.
When connecting a charger to the battery, connect the
charger positive lead to the battery positive terminal and
Reissued: 9/23/80
ELECTRICAL SYSTEM
3C21