TM 5-3810-300-24&P-3
7.1.1
STANDARD REGULATOR FOR BATTERY-CHARGING GENERATOR
(DC Charging Circuit)
To regulate the voltage and current output of the battery-
charging generator, and to maintain a fully charged
depending upon the type of electrical system. The most
representative of these devices is the "three-unit"
regulator.
These regulators are identified as:
a. A "Circuit B" unit in which the generator field
circuit passes through the regulator and returns
to ground inside the generator itself.
This
regulator must be used only with "Circuit B"
generators in which the field is internally
Fig. 1 - Typical Regulator Assembly
grounded.
As the engine starts and the generator speed increases,
b. A "Circuit A" unit in which the generator field
the current flowing through the shunt winding builds up
circuit is connected to ground within the
until it reaches the value for which the relay has been
regulator, and is used only with generators
set. At this point, sufficient magnetism overcomes the
having an externally grounded field circuit.
armature spring tension, the contact points close, and
the current flows to the battery. Then, the current which
The regulators are dust and moisture-proofed. On most
flows through the series winding is in the right direction to
applications, it is necessary to use shock mounts which
add to the magnetic force holding the armature down
insulate the regulator against vibration but necessitates
and the points closed.
the installation of a ground lead.
When the engine is slowed down or stopped, current will
The three-unit regulator consists of a cutout relay, a
begin to flow from the battery to the generator. This
voltage regulator, and a current regulator mounted in a
reverses the direction of current flow through the series
single assembly as shown in Fig. 1. These three units
winding, causing a reversal of the series winding
are basic and generally apply to most regulators in a DC
magnetic field. The magnetic field of the shunt winding
generator system.
does not reverse.
Therefore, the two windings now
oppose each other magnetically and the resultant
CUTOUT RELAY
magnetic field is not strong enough to hold the armature
down. The leaf spring pulls the armature away from the
The cutout relay has two windings assembled on one
core and the points separate, opening the circuit
core, a series winding of a few turns of heavy wire and a
between the generator and the battery.
shunt winding of many turns of fine wire. The relay core
and windings are assembled into a frame. A flat steel
CAUTION: The DC generator regulator cutout
armature is attached to the frame by a hinge so it is
relay contact points must never be closed by
centered just above the center of the core.
The
hand with the battery connected. This would
armature has two or more contact points which are
cause a high current flow through the units and
located just above a similar number of stationary contact
damage them.
points.
Operation
VOLTAGE REGULATOR
When the engine is not running, the armature contact
points of the relay are held away from the stationary
The voltage regulator has two windings on a single core.
points by tension of a leaf spring.
One is a shunt winding consisting of many
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