Buick LeSabre 1965 Service Manual page 588

1 0 - 1 8 GENERATOR-CHARGING SYSTEM
ELECTRICAL SYSTEMS
BATTERY JUNCTION
BLOCK
BAT.
ACC.
RESISTANCE
WIRE
IGN.
INDICATOR
LAMP
REGULATOR
DELCOTRON
FIELD
RELAY
VOLTAGE
REGULATOR
Figure 10-19—Delcotron Generator Wiring Circuit Diagram
flowing through either connecting
wire and causing the generator
indicator light to go out. The
field relay, therefore, has a dual
function; it not only completes the
circuit between the battery and
the field, but also acts as an
indicator light relay.
The voltage regulator armature
has two contact points which are
over and under stationary contact
points. When the voltage regu-
lator unit is not operating, the
tension of a spiral spring holds
the armature away from the core
so that the lower set of contacts
is closed. See Figure 10-19.
Generator output d e p e n d s on
two variables: Speed and field
strength. Only the field strength
can be controlled, however. Volt-
age regulator operation varies
according to operating conditions
of the car electrical system.
There are several s t a g e s of
voltage regulator operation as
follows:
a. Lower Contacts Closed
When the accessories and/or bat-
tery need a great deal of current,
but the engine speed is low, the
lower contacts will remain tightly
closed to allow full field current
of approximately 2 amperes. The
accessory load not supplied from
the generator will be supplied
from the battery.
b. Lower Contacts Vibrating
When the accessory load or bat-
tery needs are somewhat less,
or the engine speed is a little
higher, 2 amperes field current
would cause too much generator
output. Therefore, the lower volt-
age regulator contact will vibrate
to reduce field current. When the
contacts are open, the entire field
current must flow through the
resistor, which limits current to
about 3/4 ampere. While the
lower contacts are vibrating, then,
field current will be somewhere
between 2 a m p e r e s and 3/4
ampere, depending on the rate
of vibration.
c. Both Contacts Open
When the balance of the accessory
load and the engine speed is such
that approximately 3/4 ampere
field current will provide exactly
the needed generator output, the
voltage regulator armature will
"float" with neither set of con-
tacts touching. Any change in
speed or load will upset the bal-
ance, however, causing the regu-
lator contacts to again vibrate.
d. Upper Contacts
Vibrating
When the combined accessory and
battery load is low and the engine
speed is high, very little field
current is required to provide
the needed generator output. The
voltage in the charging circuit
will rise between .1 and .3 volt
and the regulator armature will
be drawn farther down to operate
on the upper set of contacts. When
the contacts are open, field cur-
rent will be about 3/4 ampere;
when the contacts are closed, the
upper armature grounds the cur-
rent from the resistor and field
c u r r e n t is zero. See Figure
10-19. While the upper contacts
are vibrating, then, field current
will be somewhere between 3/4
ampere and zero, depending on
the rate of vibration.
The regulator does not contain
a cutout relay unit. The rectifier
diodes act as one-way check
valves to prevent the battery from
discharging back through the gen-
erator, thereby making a cutout
relay unnecessary.
The regulator does not contain a
current limiting unit because an
alternating current generator acts
as its own current regulator.
10-18 TROUBLE-SHOOT-
ING CHARGING
SYSTEM
SPECIAL PRECAUTIONS: Alter-
nating current charging system
circuits are completely different