DETROIT DIESEL 53
Battery-Charging Generator 7.1
The procedure for correctly polarizing a generator will
While supporting the generator, remove the
vary with the type of electrical equipment installed and
adjusting strap bolt and washers and the mounting bolts,
upon the generator regulator wiring circuit. If the
washers and nuts. Then remove the generator.
generator field is grounded through the regulator. it Is
an "A" circuit; if it is internally grounded, it is a "B"
Remove the pulley assembly if the generator is
to be replaced.
If Delco-Remy electrical equipment is installed,
reference can be made to the Delco-Remy "Electrical
Equipment Manual" and "Test Specifications" (refer to
Install the generator drive pulley, if it was
Section 7) to determine the type of circuit applicable to
removed. Tighten the pulley retaining nut to 60 lb-ft
the regulator being used. Since it is possible to have
either an "A" or "B" circuit regulator with any given
generator, the polarizing procedures must be carefully
NOTE: If the pulley was not removed, check the
adhered to. Use of the wrong polarizing procedure or
retaining nut for proper torque.
neglecting to polarize will result in reversed generator
polarity and serious damage to electrical components.
Position the generator on the mounting brackets
and start the bolts, with lock washers, through the bolt
After ascertaining the correct circuit used, polarize the
holes in the generator end frames. If nuts are used,
generator as outlined below:
insert the bolts through the bolt holes and then install the
lock washers and nuts.
Align the threaded hole in the extension ear of
Connect a jumper lead momentarily between the
the drive end frame with the slot in the adjusting strap.
"BAT' and "GEN" terminals of the regulator.
Start the bolt, with the lock washer and plain washer,
through the slot of the adjusting strap and into the
Remove the "F" lead from the regulator and
Place the drive belts in the grooves of the
momentarily connect it to the "BAT" terminal of the
Adjust the generator belt tension as outlined in
A momentary surge of current to the generator correctly
polarizes it with respect to the battery.
Attach the wires and cables. Be sure that each
one is correctly installed in accordance with its previous
location on the generator. Keep all connections clean
Precautions must be taken when working on or around
alternators. The diodes and transistors in the alternator
circuit are very sensitive and can be easily destroyed.
Polarizing D.C Generator
Avoid grounding or shorting the output wires or the field
After each check or adjustment of the voltage regulator
wires between the generator and the regulator.
or generator, particularly after the leads have been
disconnected and then reconnected, it is necessary to
Grounding an A.C. generator's output wire or terminals,
polarize the D.C. generator before starting the engine.
which are always "hot" regardless of whether or not the
This is to ensure correct polarity with respect to the
engine is running, or accidental reversing of the battery
polarity will destroy the diodes. Grounding the field
circuit will also result in the destruction of the diodes.
Some voltage regulators provide protection against
some of these circumstances.
However, it is
Failure to polarize a D.C. generator wilt result in burned
recommended that extreme caution be used.
or stuck cutout relay contact points in the regulator, a
rundown battery and damage to the generator.
1971 General Motors Corp.
SEC. 7.1 Page 3