operation. This manual is not to be used in lieu of the
Q6-14.
When testing the diodes in an automotive
manufacturers' manuals.
alternator, which of the following multimeter
reading, if any, is considered to be a good
THREE-UNIT VIBRATING-CONTACT DC
REGULATOR
1. A high resistance reading in both direc-
tions
The vibrating-contact regulator (fig. 6-32) is the
2. A high resistance reading in one direction
type most commonly used on dc generator-equipped
and a low resistance reading in the other
vehicles. The regulator consists of a reverse current
direction
relay, a voltage regulator, a current regulator, and two
3. A low resistance reading in both direc-
resistors.
tions
There are two types of circuits in use for systems
4. None of the above
using dc generators and vibrating-contact regulators.
One is referred to as a type A or standard-duty circuit in
VOLTAGE REGULATION
which the generator field circuit is connected to the
armature terminal inside the generator and is grounded
LEARNING OBJECTIVES: Identify the
externally through the regulator contacts. The other is
components of SE voltage regulating systems.
referred to as a type B or heavy-duty circuit in which the
Identify procedures for inspecting, checking,
generator field circuit is connected to the armature
testing, and adjusting SE voltage regulating
terminal inside the regulator and is grounded inside the
system components. Identify procedures for
generator.
troubleshooting SE voltage regulating system
components. Identify procedures for repairing,
Generally, testing either type is done in the same
removing, and replacing SE voltage regulating
way, with these exceptions: the way the field control is
system components.
connected for the reverse current relay check, and the
way the generator is polarized.
Regulation of a generator's output is necessary to
prevent damage to the generator and the systems it
The regulator shown in figure 6-33 controls voltage
supplies. Without regulation, the voltage achievable is
and current by automatically cutting resistance in or out
limited only by the rpm of the driving engine.
of the field circuit of the generator. Varying the amount
of resistance in the field circuit changes the amount of
Several types of regulators are in use in today's
current passing through the generator fields. This, in
automotive systems. The basic regulators covered in
turn, changes the strength of the magnetic field
this course are the three-unit vibrating-contact, the
produced in the generator. Thus, generator output is
two-unit vibrating-contact, the two-unit transistorized,
regulated by controlling field current.
and the fully transistorized unit. Discussion of these
units is intended only to familiarize you with their
CURRENT
R E G U L ATO R
V O LTA G E
R E G U L ATO R
REVERSE
CURRENT
R E L AY
FIELD
TERMINAL
A R M AT U R E
B AT T E RY
TERMINAL
ASf06032
TERMINAL
Figure 6-32.--Three-unit, vibrating contact, dc regulator.
6-26
