Generator Control Tray (See Figure 8) - Hobart 100D20 Operation And Maintenance Manual With Illustrated Parts List

OM-2032 / Operation and Maintenance Manual
100D20 / Generator Sets
e. Control Box Assembly
The control box (Fig. 7) is a sheet metal enclosure which houses and provides mounting facilities
for generator and engine controls and monitoring equipment. The box is equipped with two,
drawer-type trays which contain generator output control devices and monitoring instruments.
Trays slide in and out on nylon rollers for easy access to internally mounted components and are
easily removable by disconnecting an "Amphenol" connector, unlocking safety latches.
Two, shielded, instrument panel lights are mounted on top of the control box front panel to
illuminate controls and instruments within the trays.

(1) Generator control tray (see Figure 8)

The generator control tray contains instruments and controls for monitoring and controlling the
generator output.
a. Resistors
Two, 20-ohm, 100-watt, ballast resistors (2) are connected in series in the generator exciter
DC field circuit.
A variable resistor (1) is connected in series between the manual control rectifier (14) and
rheostat (13) . Its purpose is to adjust the DC voltage to the rheostat and thus determine the
voltage range through which the rheostat can control generator output voltage.
b. Generator output monitors (meters)
The generator output is monitored by three instruments; a frequency meter (10, Fig. 9) a
voltmeter (9) , and an ammeter (7) . The frequency meter is a resonant-reed type which
indicates the frequency of the generator output alternating current in the range of 380 to 420
Hz (cycles per second) . The voltmeter indicates the generator output voltage in each
phase-to-neutral (A-N, B-N and C-N) or phase-to-phase (A-B, B-C and C-A) as selected by
the meter selector switch (6) and the line selector switch (5) . The voltmeter scale is
graduated 0 to 300 V and the ammeter is graduated 0 to 500 A on 90-kVA units. The
amperage value in each of the three phases may be read on the ammeter by selecting the
desired phase with switch (6) .
Chapter 1-1
Page 10
Control Box
Figure 7
March 31/94 Revised