Hobart 9OC24S Operation Manual page 55

OPERATION, MAINTENANCE, AND OVERHAUL MANUAL, TM-240A
SELF-PROPELLED GENERATOR SET, SPEC. NO. 5381A
(5) is a four-position, rotary type. A nameplate (3), located under the
switch knob, is marked and lettered to indicate the three functional
positions of the meter switch. (When the knob is pointing straight down,
the switch is OFF.) The line switch (4) is a two-position, toggle switch
used to select either line-to-neutral or line-to-line voltage to the volt-
meter. The nameplate is also marked to indicate the position of this
switch.
(d) Receptacle connector
An "Amphenol " connector (10) provides a means of quickly disconnecting
all wires to control box components.
(4 Tray
The tray (11) slides in and out on nylon rollers (9).
It is secured in
place by two captive screw fasteners (2).
(f) Manual voltage control
When the automatic manual switch (13) is placed in MANUAL position,
AC power is supplied to the rectifier (15) rather than to the automatic
voltage regulator. The DC output of the rectifier is routed to the exciter
field through a rheostat (14). The generator output voltage is thereby
manually controlled by adjustment of the rheostat.
(7) Protective relay tray (See Figure 7)
The center tray in the control box is identified as the protective relay tray
and contains electrical and electronic safety devices designed to protect the
aircraft electrical system against damage which could result from overvoltage,
undervoltage, or underfrequency. The tray also contains devices for the pro-
tection and control of the generator output electrical system. The Generator
Schematic Diagram (see 3-1, Fig. 2) shows how the protective devices are
located in the electrical system.
(a) Sensing relays
The overvoltage relay (6, Fig. 7), undervoltage relay (5), underfrequency
relay (4), and overfrequency relay (3) are connected to the generator
output leads between the generator and the load contactor. These relays
sense any abnormal condition of voltage or frequency and signal the
solid-state circuitry of the protective monitor module (1) to open the load
contactor holding circuit and disconnect the generator output to the air-
craft.
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