The voltage regulator unit operates to limit
alternator voltage to a preset value. The field relay unit
operates to connect the rotor winding and regulator
winding directly to the battery.
The operation of the double unit regulator is briefly
discussed in the following paragraphs. Refer to figure
6-35 during this operational discussion.
connected to the No. 4 terminal.
When the ignition switch is closed, the field relay
winding in the regulator is connected directly to the
battery. The magnetism created in the relay coil attracts
the relay armature toward the core, causing the contacts
to close. This connects the rotor winding directly to the
battery. Current flows from the ground of the battery,
through the rotor windings to the F terminals of the
alternator and the regulator. Current continues to flow
through the voltage regulator lower contacts, the field
Figure 6-34.--Two-unit, vibrating-contact, ac regulator.
relay contacts to the regulator No. 3 terminal, and back
to the battery.
When the alternator begins to operate, ac voltages
number of types of regulators, the vibrating-contact
are generated in the stator windings. These voltages are
regulator, shown in figure 6-34, is the one most
then changed or rectified to dc voltage, which appears
commonly used. It consists of a field relay and a voltage
at the output terminal of the alternator.
As the speed of the alternator increases, the voltage
The two-unit, double-contact regulator is suitable
at the BAT terminal of the alternator also increases.
for use in systems using either a warning light or an
This impresses a higher voltage through the field relay
ammeter. The information presented here refers to a
contacts and across the voltage regulator shunt
charging system that uses an ammeter.
Figure 6-35.--Ac charging circuit using a vibrating-contact regulator.