Overvoltage Control; Test Procedure; Purpose And Operation - Piper Navajo Chieftain PA-31-350 Service Manual

NAVAJO CHIEFTAIN SERVICE MANUAL
D.C. BUS
O/V PRECISION
O/V
FOR ADJUSTMENT
DISCONNECT
NOTE:
THIS DIAGRAM SHOWS ONLY BASIC
CONNECTIONS FOR THE PURPOSE OF
EXPLAINING ADJUSTMENT PROCEDURE.
Figure 11-20. Adjusting Regulator (Lamar)
11-25. OVERVOLTAGE CONTROL.
11-26. PURPOSE AND OPERATION.
a.
The overvoltage control is used to protect electrical circuits and electronic equipment from
excessive voltage in the event of a charging circuit malfunction.
b.
The overvoltage control consists of a mechanical relay and a solid state triggering device. The
solid state triggering device activates the mechanical relay, when the voltage reaches a preset value, thereby
opening the relay contacts and disconnecting the field circuit of the alternator.
c.
The relay contacts will remain open until the alternator switch is turned off. Figure 11-21
illustrates the overvoltage control connected in a typical Prestolite insulated field alternator.
11-27. TEST PROCEDURE. Connect the relay as shown in Figure 11-22. 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.
Reissued: 9/23/80
ELECTRICAL SYSTEM