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ALTERNATOR AND REGULATOR
8-27
FUSIBLE
SOLDERING
SCREW
I
c
I-
I
,/
NK110
Fig. 5-Voltage
Regulator Fusible Wires
terminal of the regulator and "ground." Thus, when
the ignition switch is turned "On," battery voltage
applied to the windings energizes the coil and the
magnetic force of the coil tends to attract the regu-
lator armature.
Fig. L V o l t a g e Regulator Resistance Units
regulator contacts.
A
voltage coil, (Fig.
4)
consisting of many turns of
fine wire, is connected in series between the "IGN"
SERVICE PROCEDURES
REGULATOR OPERATION
(1) When the battery line voltage is relatively low,
the current flow through the voltage coil will be low.
The magnetic force (or pull) of the voltage coil will
not be great enough to overcome the regulator arma-
ture spring tension, which is holding the armature
contact against the upper stationary contact, (Fig.
4).
Battery line voltage applied to the "IGN" terminal
causes current to flow through the regulator upper
contacts, through the "FLD" terminal of the regula-
tor and to the "insulated" brush and rotor slip ring.
The rotor field coil circuit is completed to "ground"
through the other rotor slip ring and the "ground"
brush. Inasmuch as the upper contacts are "closed,"
the field circuit resistance
is low, and maximum cur-
rent will flow through the rotor field coil. The rotor
field strength will be high, and the alternator output
will be at its maximum for any rotor speed.
(2)
As the battery line voltage increases, the mag-
netic pull of the voltage coil overcomes the armature
spring tension, and "opens" the upper contacts. The
armature contacts at this time do not touch either the
upper or lower stationary contacts. Field current now
flows through the regulator "IGN" terminal, through
resistance number one and number two, through the
"FLD" terminal, and through
the
rotor field to
ground.
The two resistors, in series with the field circuit,
reduce field current and rotor field strength, with a
corresponding reduction in alternator output voltage.
This momentarily reduces battery line voltage applied
to the regulator voltage coil. The regulator armature
spring tension overcomes the magnetic pull of the
voltage coil, closing the upper contacts.
When the electrical load requirements are rela:
tively high, the regulator armature oscillates, open-
ing and closing the upper contacts. This alternately
"puts in" and "takes out" resistance in the field cir-
cuit, and in effect limits the alternator output voltage.
(3) When the electrical load requirements are low
and the engine speed
is
high, the alternator output
voltage tends to increase. The battery line voltage
(now slightly increased) causes the regulator voltage
coil magnetic force to pull the armature contact
against the regulator lower stationary contact.
Field current flow is now through the regulator
"IGN" terminal, resistors number one and number
two, to the regulator "FLD" terminal. Since the regu-
lator armature is connected to the "FLD" terminal
and the lower contacts are closed, the current path is
through the regulator armature to the movable con-
tact and then through the lower contact to ground.
This is because the resistance to ground is less than
the alternator rotor field coil resistance.
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