Balancing Circuit Operation - Piper SENECA II Service Manual

PIPER SENECA II SERVICE MANUAL
BUS
FIELD
/ ENCAPSULATED
______L_
CONTROL ASSY
i
-:_-----r--=----r--=----+---------t--t--~
Rl2
02
R6
DI
R7
R9
I
L _ _
_ _ _ J
R3
PAR
GND
Figure 11-10. Regulator Diagram
11-20. BALANCING CIRCUIT OPERATION. (Considering two identical alternators and regulators having
the "PAR" terminals of the regulators connected.)
a. Balancing circuit operation is initiated within one regulator whenever individual field voltages
delivered by the regulator units to their related alternators are not equal.
b. When a difference in individual field voltages occurs, one-half the difference is impressed across
R 12 within each regulator and is thus applied to the input of Q5.
c. In that regulator which is delivering the lower field voltage, the polarity of R 12 voltage drop
causes Q5 collector current flow.
d. Q5 collector current flow results in conduction occurring in the collector circuit of Q6.
e. Q6 collector current flows from regulator divider R l /R2+R3 through limiting resist\
ll
R 1 7 to
ground.
f.
Conduction through R17 effectively alters the ratio of the regulator dividt:1 R.l/R2+1{3 in the
direction to increase Ql collector current flow.
g. As described above under REGULATING CIRCUIT OPERATION, increased QI current results
in increased output from the regulator to the field of its related alternator.
h. Feedback action results in Q6 collector current stabilizing at a value that results in nearly equal
field voltage being delivered by the two regulators to their respective alternator fields.
i.
The balancing circuit will thus automatically maintain, at a low value, the difference voltage
applied to the alternator fields. In a parallel system having identical alternators operating at the same
RPM,
the output currents of the alternators will thus be maintained nearly equal.
j. 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.
Reissued: 10/11/79
2G10
ELECTRICAL SYSTEM