Piper Comanche PA-24 Service Manual page 709

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PIPER COMANCHE SERVICE MANUAL
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FIGURE 9·27 •• APPLICATION OF
OVERVOL T AGE CONTROL
c. Cau.tion Notes:
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FIGURe 9-27 •• TESTING OVER VOL T AGE
CONTROL
1. Use only witb inallilled (llngrolllllled) field Ille"",lor •.
2. Reglllator base IIIWIt bave a goac! grollllll cormection.
3. Do not connect around powftr to aircraft until voltase "'Iwator "I" terminal has been
disconnected from electtical system.
4. Do not (even momentarily) connect the two voltl", regulator terminals together.
5. Do
Dot
connect battery
iDlO
system with aol.rity reversed.
6. 00 not force the volta .. adjustment screw.
/. This is a sealed unit and !'lot repairable. Replace with a new unit.
9-615. O ••
",olt.,. C.nt,.1.
9-61t. Purpo,e Anc! O,.ration .
•. The overvoltage control is used to protect electrical circuits and electronic equipment
from excessive voltale in the event of. eharliq circuit malfunction.
b. The overvoltage control consists of a mechanical relay and a solid state trillering de·
vice. The solid state trillennl device acuvates
the
mechanical relay •• hen.
the
voltage reac!'1es
a
~reset
value. thereby OpeDinl the relay contacts and disconnectinl the field
ClrC" •
.u
t of t
he
al ternatot.
c. The relay contacts will relDain open until tbe alternator switch
l.S
twned.
off. Figure 9-27r
illustrates the overvoltale control connected in a typical ?restoUte Insulated field alternator.
9-610. Too' Procedur •. Connect tbe relay as shown in Fillll'e 9-275. Use a l()().ohm potenti.
ometer of lS-watt rating, or more, to adj\lSt the voltage. The voltmeter is used to read the voltage
until the :elay ~pens. at which time the voltmeter readinc will drop to zero. See tabulation for
voltage reading. Test figures are at 7S degrees Fahrenheit. These units are not adjustable. Re-
place the overvoltage control if it does not test to specifications.
Relay contacts open between 16.2 .ad 16.8-volts. Use 18 o. 24·vollS to test.
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ELECTRICAL SYSTEM
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