Piper SEMINOLE PA-44-180, Maintenance Manual

Page: 225 / 881

10. In whichever regulator of a pair is set to deliver the highest voltage, the balancing circuits are inactive.
Thus system voltage is determined by the regulator of a pair which is set to higher voltage. The lower
set regulator will adjust itself automatically, as described above, to deliver the same field voltage as the
one which is set higher, within the limits of its design capability.
11. The balancing regulator system as described provides for automatic load balancing of parallel operated
alternators having independent field excitation circuits. The pilot can, while in flight, remove either
alternator system completely from the aircraft system and maintain operation of the other system.
CHECKING OVERVOLTAGE RELAY. (S/N 44-7995001 thru 44-8195026 and all PA-44-180T’s)
The relay may be tested with the use of a good quality, accurate voltmeter, with a scale of a least 20 volts
and a suitable power supply, with an output of at least 20 volts, or sufficient batteries with a voltage divider to
regulator voltage. The test equipment may be connected as follows:
1. B+ is connected to “BAT” terminal of the overvoltage control.
2. B- is connected to the frame of the overvoltage control.
3. Be sure both connections are secure and connected to a clean, bright surface.
4. Connect the positive lead of the voltmeter to the “BAT” terminal of the overvoltage control.
5. Connect the negative lead of the voltmeter to the frame of the overvoltage control.
6. The overvoltage control is set to operate between 16.2 to 17.3 volts. Increase power supply voltage
until an audible click is heard when the relay operates.
7. If the relay does not operate between 16.2 to 17.3 volts the overvoltage relay s out of specification and
must be replaced.
LAMAR MODEL NO. B-00392-1 ALT E R N ATOR VO LTAGE REGULATOR. (S/N’S 4495001 AND UP)
The voltage regulators and shunts are mounted on a panel that is secured to the left bulkhead at F. S .
35.000. They are accessible by opening the aircraft nose section. The top units are connected to the left
engine alternator and the bottom units are connected to the right side.
Figure 24-7. Electrical Component Location (Lamar Model No. B-00392-1)
(S/N 4495001 and up)
PIPER AIRCRAFT
PA - 4 4 - 1 8 0 / 1 8 0 T
AIRPLANE MAINTENANCE MANUAL
24 -23-09
Page 24-21
Revised: June 20, 1995
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