Piper Cherokee Six - Electrical Power Supply

SECTION X
ELECTRICAL
SYSTEM
10-1. DESCRIPTION.
The
electrical
system of
the PA-32
is a 14-volt,
direct
current,
single
wire,
negative
ground
system. All
electrical
equipment
is grounded
to
the metal
structure
of
the airplane.
therefore, the
structure
takes the place
of the second
wire. A 12-volt
battery
is
incorporated
in the system
to
furnish power
for
starting and
as a reserve
power
source
in
case
of alternator
failure.
The battery
and
alternator
are
both
connected
to the
bus
bar:
from which
all the
electrical
equipment
is powered,
with
the exception
of the
starter
which
receives its
power from
the load side
of the battery.
The master
switch controls
the battery
relay and
the alternator
field
circuit.
The master
switch
must be
on before
any electrical
equipment
will operate.
The
Cherokee
Six can
be equipped
with
the standard
position
lights,
anti-collision
lights,
and one landing
light
located in
the nose cowl
assembly.
10-2. TROUBLESHOOTING.
Troubles
peculiar
to the
electrical
system are
listed in
Table
X-III at
the back
of this section
along
with their
probable
causes
and suggested
remedies.
The wiring
diagrams
included
in back
of this section
will
give a physical
breakdown
of the
different
electrical
circuits used
in this
airplane.
After the
trouble
has been
corrected,
check
the entire
electrical
system
for security
and
operation
of its
components.
10-3.
ELECTRICAL
POWER
SUPPLY.
The
electrical
power
is supplied
by
one
12-volt
battery
and a
14-volt direct
current alternator.
The
alternator is
located on the
front lower
right
side of
the engine
and utilizes
a belt
drive from
the engine
crankshaft.
Many
advantages
both
in operation
and
maintenance
are
derived from
this system.
The
main advantage
is
that
full
electrical
power
output
is available
at lower
engine
RPM.
The
alternator
has no armature
or commutator
and
only a small
pair of carbon
brushes.
which
make
contact
with a
pair of
copper
slip rings.
The
rotating
member
of the
alternator.
known
as the
rotor, is
actually
the field
windings.
The rotor
draws
only 1/20th
of the
current
output.
Therefore,
there
is very
little friction
and
negligible
wear and
heat in
this
area.
The alternating
current
is converted
to direct
current by
diodes pressed
into
the end
bell
housing of
the alternator.
The
diodes
are highly
reliable
solid-state
devices,
but are
easily
damaged
if current
flow is reversed
through
them.
The
alternator
system
does not
require a
reverse current
relay,
because
of the
high back
resistance
of the
diodes
and the
inability
of the
alternator
to
draw current
or
motorize.
A
current
regulator
is unnecessary
because
the windings
have
been designed
to
limit the
maximum
current
available.
Therefore,
the
voltage
control
is the only
control
needed.
ELECTRICAL
SYSTEM
Revised:
7/28/75
PIPER
CHEROKEE
SIX
SERVICE
MANUAL
3A14