4. P l a c e t h e D C / A M M E T E R R A N G E
i n d i c a t o r ( 6 ) a n d E X T E R NA L P OW E R
SELECTOR switches (4 and 8, fig. 7-63) in the
indicator (5) should illuminate.
2000A position.
8. Turn on the AC PANEL LIGHTS toggle switch
5. Place the CONTROL CIRCUIT switch (7, fig.
(10, fig. 7-62), and adjust the INTENSITY
7-62) in the dc position. The cooling fans should
control knob (9) for the desired panel
start and the WIND SWITCH CLOSED
illumination level.
indicator (6) should illuminate.
OPERATING PROCEDURES
6. Turn on the dc PANEL LIGHTS toggle switch
(3, fig. 7-62) and adjust INTENSITY control
The load bank has the capability to test straight dc
knob (2) for desired panel illumination level.
output (common bus), dc jet starting output (split bus),
Control Power Application, AC Source
and ac output.
If power for operating the load bank is supplied by
Common Bus DC Operation
the 115/200-volt, 400-Hz, ac output of the power plant,
proceed as follows:
To test power plants by using the aircraft servicing
1. Connect the 115/200-volt power cable to the ac
input of the load bank, proceed as follows:
input connection facilities on the ac input panel
1. Place the BUS SELECTOR switch (12, fig.
(3, fig. 7-61).
7-63) in the COMMON position.
2. Operate the power plant to apply 115/200 volts
2. P l a c e t h e D C C O M M O N B U S L O A D
to the load bank.
PROGRAM SELECTOR switch (2, fig. 7-63),
3. Set the METER PHASE SELECTOR switch
in the desired position.
(11, fig. 7-64) to each of its three positions and
verify that the SINGLE PHASE VOLTS meter
a. I n t h e C O N T I N U O U S p o s i t i o n , a
(13) indicates 115 volts for each phase.
continuous load of up to 3,000 amperes can
be applied for as long as the COMMON
NOTE: The load bank will not operate if the ac
BUS SHOCK LOAD toggle switch (13) is in
input exceeds 130 volts in phase A, nor can it be reset
the ON position.
until the ac input is reduced below 125 volts.
b. In the 5-MIN position, a load of up to 3,000
4. Verify that the FREQUENCY meter (4, fig.
amperes can be applied when the
7-64) indicates 400 Hz.
COMMON BUS SHOCK LOAD switch is
NOTE: The load bank will not operate if the ac
in the ON position.
input frequency is less than 370 Hz, nor can it be reset
c. The load is automatically dropped after 5
until the frequency is increased to at least 377 Hz.
minutes. In the 5-SEC position, the load is
automatically dropped after 5 seconds.
5. Note the bright illumination of either the
PHASE SEQUENCE ABC indicator (1, fig.
3. S e l e c t t h e d e s i r e d l o a d b y p l a c i n g t h e
7 - 6 4 ) o r t h e P H A S E S E QU E N C E C BA
appropriate LOAD SELECTORS DC AMPS
indicator (3). Load bank circuits are not affected
switches (10 and 14, fig. 7-63) in the ON
by the phase sequence of input power. Improper
position.
phase sequence may indicate the wrong cable
connections or faulty operation of the power
4. Place the COMMON BUS SHOCK LOAD
plant.
switch (13, 7-63) in the ON position and read the
DC AMPS meters (3 and 9). The actual load is
6. Place the AMMETER-WATTMETER RANGE
SELECTOR switch (8, fig. 7-64) in the 1600 A
the sum of the two meter indications.
position.
a. If either of the meters indicates near the low
7. Place the CONTROL CIRCUIT switch (7, fig.
end of its scale, place the corresponding DC
7-62) in the ac position. The cooling fans should
AMMETER RANGE SELECTOR switch
start, and the WIND SWITCH CLOSED
(4 or 8, fig. 7-63) in the position closest to,
but greater than, the applied dc load.
7-61
