Voltage Regulator 1-1 - Hobart 6921 Series Operation And Maintenance Manual

OM-2040 / Operation and Maintenance Manual
90D20 / Generator Sets
g. Voltage Regulator
NOTE: The following references to the voltage regulator are to the Hobart magnetic-amplifier type
voltage regulator, Part No. 430391C, which is used on many of the generator set specifications
covered by this manual. Some generator set specifications covered by this manual employ a
newer solid state voltage regulator, Part No. 489812 or 489812A. For a detailed description of
the solid state voltage regulators, refer to Voltage Regulator Manual OM-2020 or OM-2020A in
Chapter 6 of this manual.
The voltage regulator (Fig. 13) is located on the left side of the machine behind the engine
compartment. The regulator is accessible for adjustment by opening the door on the left side.
Although a separate regulator manual is supplied with the generator set, a brief, working description
is given here.
The voltage regulator is designed to provide 1% voltage regulation with 25-second recovery time for
all loads up to 100% of rated load on a three-phase, four-wire, 115/200-volt, 400-Hz, brushless
generator. This regulator provides field excitation power for the rotary exciter and regulates
generator output voltage by varying the exciter field power as required to meet varying load
conditions. Thus, the generator output is held at a constant voltage. The maximum continuous
rating of this regulator is 4.0 amperes at 140 volts DC.
Any deviation of the generator output voltage from its set level is sensed by the voltage detection and
comparison circuits. A signal is fed from the comparison circuit into the transistorized, preamplifier,
preamplified, and used to drive the magnetic amplifier. The magnetic amplifier output changes in
response to this signal, changing the field power of the rotary exciter enough to return the generator
voltage to its regulated value. The voltage at which the generator is regulated may be adjusted with
the voltage adjustment rheostat (2, Fig. 12) .
February 28/94
Revised
Engine Test Panel
Figure 12
Chapter 1-1
Page 19