Application Of Overvoltage Control; Testing Overvoltage Control - Piper Navajo PA-31 Service Manual

OVER
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Figure 11-37. Application of
Figure 11-38. Testing Overvoltage
Overvoltage Control Control
11-54. TEST PROCEDURE. Connect the relay as shown in Figure 11-38. Use a 100-ohm
potentiometer of 15-watt rating, or more, to adjust the voltage. The voltmeter is used to
read the voltage until the relay opens, at which time the voltmeter reading will drop to zero.
See tabulation for voltage reading. Test figures are at 75 degrees Fahrenheit. Relay contacts
open between 31.50 and 32.50-volts. Use 36-volts to test.
NOTE
These units are not adjustable. Replace the overvoltage
control if it does not test to specifications.
11-55. OVERVOLTAGE
RELAY OPERATIONAL CHECK (NON-PARALLELING
SYSTEM). This check should be made at each 500 hour inspection, per the following
instructions:
a. Pull out (OFF) all circuit breakers except the main and auxiliary voltage regulators
(5-amp).
b. Turn off the right and left alternator output circuit breaker switches (90-amp).
c. Set the voltage regulator selector switch to MAIN.
d. Obtain a variable D.C. voltage power supply and set it to zero output.
e. Connect the power supply to the aircraft through the external power receptacle. On
aircraft without an external power receptacle, disconnect the battery cables and connect the
power supply to the cables.
f.
Obtain a volt/ohmmeter and set it to 60 volts D.C. Connect the meter VOM lead to
the output (REG.) terminal of the MAIN overvoltage relay. Connect the meter COM lead to
the airframe ground.
Reissued: 10/12/79
ELECTRICAL SYSTEM
PIPER NAVAJO SERVICE MANUAL
4C14