Hobart Brothers 6910, Руководство по эксплуатации и техническому обслуживанию с иллюстрированным списком запасных частей

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(1) Generator control tray (See Figure 7)
The generator control tray contains instruments and controls for monitoring and controlling the
generator output.
(a) Resistors
Two, 10-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 rec-
tifier (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) , a voltmeter
(9) , and an ammeter (7) . The frequency meter is a resonant-reed type, and indicates the fre-
quency 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) . (These switches will be described below.) The voltmeter
has a 3-1/2-inch face and the scale is graduated 0 to 300 V. The ammeter is also 3-1/2-inch
size and is graduated 0 to 500 A. The amperage value in each of the three phases may be
read on the ammeter by selecting the desired phase with switch
(6) . Three ammeter current
transformers
(Ref. 4, Fig. 11)
lower the output load current to a lesser value, of definite ratio,
which will operate the ammeter movement without damage. The ammeter dial scale is gradu-
ated and numbered so that the pointer will indicate the true load current value rather than the
meter movement current.
(c) Meter and line switches
These switches provide a means of selecting and determining which phase of voltage and
current is indicated on the voltmeter and ammeter and whether the voltage is line-to-neutral
or line-to-line. The meter switch
(6) is a four-position, rotary type. A nameplate (4) , located un-
der 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
(5)
is a twoposition, toggle switch used to select either line-to-neutral or lineto-line voltage to
the voltmeter. The nameplate is also marked to indicate the position of this switch.
(d) Receptacle connector
An “Amphenol” connector (12) provides a means of quickly disconnecting all wires to control
box components.
(e) Tray
The tray
(15)
slides in and out on nylon rollers. It is secured in place by a twist-lock, screw fas-
tener (8) .
(f) Manual voltage control
When the automatic manual switch (11) is placed in MANUAL position, AC power is supplied
to the rectifier
(14)
rather than to the automatic voltage regulator. The DC output of the recti-
fier is routed to the exciter field through a rheostat (13) . The generator output voltage is
thereby manually controlled by adjustment of the rheostat.
(g) Excitation-deenergization relay
The purpose of this relay
(3)
is to allow automatic excitation to be connected to the exciter
field only when engine speed is being controlled by the electric governor.
OM-2028
May 1/91 Revised 1-1
Page 13