Application Of Over-Voltage Control; Testing Over-Voltage Control - Piper APACHE PA-23-235 Service Manual

PIPER AZTEC SERVICE MANUAL
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Figure 11-55. Application of Over-Voltage
Control
Figure 11-56. Testing Over-Voltage Control
11-98. 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 mechnical relay and a solid state triggering device. The solid
state triggering device activates the mechanical relay, when the voltage reaches a present 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 1 1-55 illustrates
the overvoltage control connected in a typical Prestolite insulated field alternator.
1 1-99. TEST PROCEDURE. Connect the relay as shown in Figure 11-56. 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 relays opens, at
which time the voltmeter reading will drop to zero. See tabulation for voltage reading. Test figures are at 75
degrees Fahrenheit.
a.
14-volt system: Relay contacts open between 15.5 and 16.5 volts. Use 18 or 24 volts to test.
ELECTRICAL SYSTEM
4F9
Reissued: 2 18 81
4F9