Hobart 9OC24S Operation Manual page 59

GENERATOR DIVISION
HOIWRT BROTHERS COMPANY
OPERATION, MAINTENANCE, AND OVERHAUL MANUAL, TM-240A
SELF-PROPELLED GENERATOR SET, SPEC. NO. 5381A
(i) Diode, capacitor and terminal board
A terminal board (20) is used to mount and connect a diode (19) and a
capacitor (21) into the fuse-interlock relay coil circuit. Their
purpose
is to prevent an inductive "spike" in the 12-V DC circuit from triggering
an SCR in the protective monitor module (1) and turning on an indicating
light when no fault exists.
(i) Fuses
A fuse (22) is located in the load contactor hold circuit to protect the
power module (1) in case of rectifier failure. Another fuse (14) protects
the 12-V DC, protective monitor circuit.
(8) Voltage regulator tray (See Fig. 8)
The voltage regulator tray contains only the static voltage regulator (2). The
tray (1) slides in and out on nylon rollers (3) and is secured in place by captive
screw fastenersthe same as the other two trays described above.
Although a complete manual, TM-232, for the voltage regulator accompanies
these instructions, 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, regulated level
is sensed by the voltage detection and comparison circuits.
A signal is fed
from the comparison circuit into the transistorized pre-amplifier, amplified,
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 (Fig. 9, item 2).
(a) Controls
The rheostat (Fig. 9, item 2) is used to adjust the regulated voltage
value of the generator output.
by a potentiometer (4).
Compensation for cable size is adjusted
C bl I
a e ength is compensated for by adjustment
Page 23