DETROIT DIESEL 53
Battery-Charging Generator Regulator 7.1.1
through the field relay contacts across the regulator
acts to prevent oxidation of the voltage regulator
shunt winding. The magnetism created in the winding
contacts. Regulators incorporating the choke coil are
causes the voltage contacts to open, thus causing the
identified by a spot of green paint on the regulator base,
transistor to shut off the field current. The generator
next to the single mounting bolt hole.
voltage then decreases and the voltage contacts
reclose. This cycle repeats many times per second,
CAUTION: A capacitor must not be installed unless
thereby limiting the generator voltage to the value for
the transistorized regulator incorporates the choke
which the regulator is set.
coil.
The magnetism produced in an accelerator winding,
Operation
when the voltage contacts are closed, aids the shunt
When the engine starting switch is closed, the field relay
winding in opening the contacts. When the contacts are
winding is energized and causes the contacts to close.
open, the absence of the magnetism i n the accelerator
Current then flows from the battery through the relay
winding allows the spring to immediately reclose the
contacts to the regulator "F2" terminal. From this point,
contacts. This action speeds up the vibration of the
the current flows through the generator field winding and
contacts.
then through the transistor and voltage contact points to
ground.
CAUTION: Do not short across or ground any of
the terminals on the regulator or the generator
As the generator speed increases, the increased voltage
and do not attempt to polarize the generator.
from the generator "BAT' terminal is impressed
TRANSISTOR REGULATOR
The voltage at which the generator operates is
The transistor regulator is composed principally of
determined by the regulator adjustment. Once adjusted,
transistors, diodes, capacitors and resistors to form a
the generator voltage remains almost constant, since
completely static electrical unit containing no moving
the regulator is unaffected by length of service, changes
parts.
in temperature or changes in generator output and
speed.
The transistor is an electrical device which limits the
generator voltage to a preset value by controlling the
A separately mounted field relay connects the regulator
generator field current. The diodes, capacitors and
"POS" terminal and the generator field windings to the
resistors act together to aid the transistor in
battery when the engine starting switch is closed.
performing this function, which is the only function that
the regulator performs in the charging circuit.
Fig. 4. Transistor Regulator (Negative Ground Circuits Only)
1971 General Motors Corp
May, 1971
SEC. 7.1.1 Page 5
