Hobart 6824-1, Operation And Maintenance Manual, Page: 77 / 214

(18)
Open the protective relay tray and place the test bank switch
(34, Fig. 2)
in TEST BANK
position.
(19) Again place the load contactor switch (20) in the top, CLOSE position. Light (22) should glow
GREEN and remain ON when the switch is released and allowed to return to the center ON
position. This indicates that the test bank switch
(34) is functioning to by-pass the plug interlock
relay.
(20) Return the test bank switch to AIRCRAFT position. The load contactor should open at once and
the green indicating light
(22)
should go off.
(21) Connect a source of 24-V DC power (two twelve-volt batteries connected in series) to terminals
“N” and “F” (or “E”) at the output terminal panel. Connection polarity should be: MINUS to
terminal N and PLUS to terminal E or F.
(22) With test-bank switch in AIRCRAFT position, hold the contactor operating switch (20) in top,
CLOSE position momentarily. The generator “on” indicating light
(22)
should glow GREEN and
remain on when the switch is released and allowed to return to the center ON position. This
indicates that the load contactor is closed and the plug interlock relay is functioning properly.
(23)
Apply 1/3 to 1/2 load at the load bank and allow the unit to run for 15 to 30 minutes. Observe
operation of all monitoring instruments.
(24) Increase load bank resistance to apply a full load.
(25) Check operation of the governor by observing the frequency meter (1, Fig. 2) when generator is
switched from no-load to full-load and vice versa. Use the contactor control switch (20) to apply
and remove load several times. Frequency drop should be no more than 1 Hz. Adjust governor
if necessary
(see Para. 4, E, (3)).
(26) Follow instructions in Para. 4, B, (2) (b) to set voltage regulator linedrop compensation
potentiometers (Ref. Figure 2, items (38) and (39)). Set knob pointer on cable size
potentiometer (39) to size (2/0, 4/0, etc.) of cable being used. Set knob pointer on cable length
potentiometer (38) to length (20 feet, 40 feet, etc.) of cable being used. See instruction plate
(mounted below knobs).
(27)
Check voltage regulator, at intervals, from no-load to full load, and on up to 125% load. Observe
and note voltage at various loads. Voltages should vary no more than plus or minus 1% from
115 V.
(28) Check accuracy of voltmeter.
a. Open generator control tray (14, Fig. 2).
b. Connect a master voltmeter of known accuracy to terminals of the voltmeter (2).
c. Compare unit voltmeter reading with master meter. Error must not exceed 2% of full scale.
(29) Check accuracy of AC ammeter.
a. Connect a master ammeter of known accuracy to the AC ammeter (4) terminals.
b. Compare unit ammeter reading with master meter under various loads. Error must not
exceed 4% of full scale.
(30) Check operation of meter selector switch (5). A voltage value should be shown in each switch
position.
(31) Check operation of the line switch (6). A normal voltage of 115 V AC should be indicated when
the switch is in LINE-TO-NEUTRAL position. A voltage of approximately 200 V AC should be
indicated when the switch is placed in LINE-TO-LINE position.
(32) Check accuracy of frequency meter.
OM-499
May 31/94 Revised 2-3
Page 7