NOTE: To ensure accurately timed programs, do
OFF or RUN position for 60 seconds before
starting another test cycle.
not change the position of the DC COMMON BUS
LOAD PROGRAM SELECTOR switch (2, fig. 7-63)
9. After completing the tests of the power plant,
unless the COMMON BUS SHOCK LOAD switch
proceed as follows:
(13) is in the OFF position.
a. Place both SHOCK LOAD switches (11 and
13, fig. 7-63) in the OFF position.
7. Set the SPLIT BUS PROGRAM SELECTOR
switch (6, fig. 7-63) to the desired
b. Turn the VARIABLE 0-55 AMPS controls
position--HARD START or SOFT START.
(1 and 4, fig. 7-62) fully counterclockwise.
a. In the HARD START position, the desired
c. Disconnect the power plant from the load
hard start load must be selected by turning
bank or shut down the power plant by
on the appropriate LOAD SELECTOR DC
appropriate switching as described in the
AMPS toggle switch (10, 7-63).
power plant operating manual.
b. In the SOFT START position, the load is
automatically selected, regardless of the
WARNING
switch (10) positions. Only power plants
Always make certain that the power supply to the
equipped with soft start characteristics
load bank has been completely cut off (check the
(reduced voltage output for first 10 seconds
DC VOLT meters for indications) before
of test) are tested using the soft start
disconnecting power cables.
program.
8. Hold the SPLIT BUS SHOCK LOAD switch
AC Operation
(11, fig. 7-63) in the START position until the
DC AMPS meter (9) indicates that the load is
To test the 115/200 volts, three-phase, four-wire,
applied, and then release the switch to the RUN
400-Hz output of a power plant, proceed as follows:
position. In a hard start program, the load is
1. Place the AC LOAD PROGRAM SELECTOR
dropped automatically after 20 seconds; it is
switch (5, fig. 7-64) in the desired position.
maintained in an OFF position for 40 seconds,
during which time the load cannot be reapplied.
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
In a soft start program, the load is automatically
continuous load of up to 187.5 KVA, at any
selected at 1,000 amperes at 5 volts for 10
power factor between 1.0 and 0.2, can be
seconds, and then 200 amperes at 28 volts for 10
applied for as long as the SHOCK LOAD
seconds, after which the 40-second OFF
SWITCH (19, fig. 7-64) is in the ON
condition occurs.
position.
a. P l a c e t h e D C A M M E T E R R A N G E
b. In the 5-MIN position, a load of up to 281.5
SELECTOR switch (8, fig. 7-63) in the
KVA, at any power factor between 1.0 and
position closest to, but greater than, the dc
0.47, can be applied when the SHOCK
LOAD switch (19) is placed in the ON
load applied.
position. The load is dropped automatically
b. The load may be dropped at any time during
after 5 minutes.
the program by placing the SPLIT BUS
c. In the 5-SEC position, a load of up to 375.5
SHOCK LOAD switch (11, 7-63) in the
KVA, at any power factor between 1.0 and
OFF position. However, if the load is
0.57, can be applied when the SHOCK
dropped in this manner during a timed
LOAD switch (19) is placed in the ON
sequence, the next test cycle (normally 20
position. The load is dropped automatically
seconds) is shortened, depending upon how
after 5 seconds.
long the switch was in the RUN position
before the load drop and how much time was
2. From the required KVA and PF (power factor)
allowed before the start of the next cycle. For
load specifications for the power plant to be
a full reset, allow the switch to remain in the
tested, calculate the following corresponding
7-63
