a. 100-ampere. The 100-ampere alternator (6) is an engine driven
generator, with three functional parts: rotor, stator, and brushes. It provides a
three-phase AC current output whose amplitude is controlled by the current in the
field winding of the rotor.
b. Rectifier. The rectifier is a separate unit (16). It is a selenium
rectifier that changes the three-phase AC current to direct current and is
connected to the alternator and regulator by cables.
c. Regulator. The regulator (7) senses the output voltage of the rectifier
(16) and controls the alternator (6) output to the rectifier.
(1) The regulator is a solid-state voltage regulator designed for self-
load limiting alternators. It is a direct replacement item for the older carbon
(2) It utilizes silicon transistors to switch the field current of the
alternator ON and OFF. It also incorporates a load relay for disconnecting the
d. Testing the l00-ampere alternator. The alternator may be tested on the
test stand without a voltage regulator. However, a rectifier is required so the DC
output can be used to load the alternator. Foldout 7 shows the cable hookup; in
particular, note the rectifier connection.
(1) Unlike the 60-ampere generator, the test stand is connected between
the alternator and rectifier. This being the case, each phase of the alternator
can be monitored and checked.
(2) The AC voltmeter checks the voltage between the phases and the AC
ammeter checks the current in each phase.
(3) The AC voltage between the phases should be equal.
(4) The AC ammeter should indicate 100 amperes as the 100-ampere load is
applied to the output of the rectifier.
(5) The DC ammeter monitoring the field current should not indicate less
than 9 or greater than 12 amperes.
7. TESTING THE 100-AMPERE REGULATOR. In testing the regulator, the alternator,
rectifier, and regulator are operationally connected. It is necessary that the
alternator and rectifier be known to be operational. In other words, in order to
verify the regulator, the alternator and rectifier have to functionally meet their
specifications. Connection of the three components is shown in foldout 8.
a. The alternator is mounted to the test stand and its pulley calibrated as
previously discussed. Make certain that all the controls are positioned according
to table 1.
b. Take notice that the bus bar links between B+ and G+ and B- and G- have
been removed. This is very important.
c. The rectifier is mounted in the cooling chamber where the blower
circulates air. There is an interlock switch that actuates when the chamber door
is closed, so be certain the cooling chamber door is closed or the stand will not
d. The regulator is mounted in a special bracket which is connected to the
mounting base located in front of the rectifier cooling chamber.
OS 010, 4-P17