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13-26
PART
13·5
LUCAS
ALTERNATOR REGULATOR
Section
Page
Section
I Description and Operation ........
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..... 13-26
2 In-Car Tests
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.13-29
LUCAS ALTERNATOR
REGULATOR
Two models of alternator voltage
regulator are used
.
The 9 ATR model voltage regulator
is mounted on the fender apron and
is matched to the 14 AC model
alternator,
Fig.34.
The 13 ATR is integral with the
14 ACR model alternator and is
mounted inside the slip ring and
head.
Fig.
33.
The two regulators have identical
circuits and the description and mode
of operation described herein apply
to
both.
Both regulators are non-adjustable
and if tested and found defective
must be replaced
.
DESCRIPTION
The regulator consists of a com-
pletely static compact assembly of
transistors,
diodes, resistors and cap-
acitors soldered to a printed circuit
FIG. 33- 13 ATR Regulator
board. In effect, the operation is
similar to that of the conventional
electro-mechanical regulator in that
the alternator field current is varied
to maintain the output voltage within
close limits, but switching is per-
formed by transistors instead of
vibrating contacts and a Zener diode
provides the voltage reference in
place of the usual electro-magnet and
tension spring. The unit incorporates
a radio interference suppression cap-
acitor.
Since current can only flow in one
direction through the alternator out-
put diodes, no cut-out relay device is
required .. Neither is a current limiting
device needed, due to the inherent
self-regulating characteristic of altern-
ators.
The control unit and alternator
field windings are isolated from the
battery when the engine is stationary
by means of the ignition switch.
OPERATION
In effect, the operation is similar
to that of the conventional electro-
mechanical regulator in that the alter-
nator field current is varied
·
to main-
tain the stator output voltage within
close limits, but switching is effected
with transistors instead of vibrating
contacts, and a Zener
diod~provides
the voltage reference in place of the
usual voltage coil and tension spring.
As the alternator is accelerated from
rest, its output voltage is allowed to
build up until it reaches a limiting
value set by the Zener diode and a
fixed resistance. At this point the
field current is reduced by the action
of a transistor amplifier. Any further
small increase in voltage beyond the
limiting value serves to switch out
the field completely -
again by
transistor action.
When the ignition is switched on
the control unit is connected to the
battery through the indicator light,
FIG. 34-9 ATR Regulator
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