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