Overvoltage Relay Operational Check (Paralleling System); Application Of Overvoltage Control; Testing Overvoltage Control - Piper Navajo Chieftain PA-31-350 Service Manual

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NAVAJO CHIEFTAIN SERVICE MANUAL
OVERVOLTAGE
CONTROL
1242 C
ALTERNATOR
VOLTMETER
ALTERNATOR
SWITCH
+
BATTERY
BATTERY
Figure 11-21. Application of Overvoltage Control
Figure 11-22. Testing Overvoltage Control
11-28. OVERVOLTAGE RELAY OPERATIONAL CHECK (Paralleling System). This check should be
accomplished at each 500 hour inspection, per the following instructions:
a. Pull all circuit breakers to the out (OFF) position except the left and right voltage regulator (5
amp) circuit breakers.
b. Obtain a variable D.C. voltage power supply and set it to zero output.
c.
Connect the power supply to the aircraft through the external power receptacle.
d. Turn ON the left alternator section of the Dual Master Switch.
e.
Obtain a volt/ohmmeter and set it to 60 volts D.C. Connect the positive lead of the VOM to the
output (LOAD) terminal of the LEFT overvoltage relay. Connect the negative lead of the VOM to airframe
ground.
f. Increase the output voltage of the variable D.C. power supply until the LEFT overvoltage relay
trips out. (An audible click will be heard when the relay operates and the VOM needle must drop to zero
volts.) Record the power supply voltmeter reading which was indicated just prior to the overvoltage relay
operating. Voltage limits are: Min. 31.50 volts - Max. 32.50 volts.
g. Reduce the power supply to zero. Turn OFF the left alternator section of the Dual Master
Switch. Another click will be heard when the overvoltage relay resets itself for normal operation.
h. Turn ON the right alternator section of the Dual Master Switch. Reconnect the volt/ohmmeter to
the right overvoltage relay and repeat steps f and g.
Reissued: 9/23/80
ELECTRICAL SYSTEM
3D10