©
National Instruments Corp.
17
NI 9478 Operating Instructions and Specifications
Example Two
Yo
u
are driving a load with 2.0 meters of cable thro
u
gh a cycle in
which the NI 9478 first is constantly on and passing 3 A of c
u
rrent
for 0.25 seconds, then drives the load at 20 kHz with 1.25 A c
u
rrent
for 1.25 seconds, then drives the load off for 4 seconds. While the
NI 9478 is constantly on, the o
u
tp
u
t freq
u
ency is 0 kHz and the
channel
u
ses 36% (4%
×
3
2
) of the total power b
u
shows that while the NI 9478 is driving at 20 kHz, the channel
u
ses 14.8% of the total power b
u
dget. While the NI 9478 is off, the
channel
u
ses 0% of the power b
u
dget. The average percentage of
total allowable power over the complete 5.5 second cycle is 5%,
as shown in the following eq
u
ation.
36% 0.25s
(
)
14.8% 1.25 s
(
)
0% 4s
( )
+
+
5.5s
-------------------------------------------------------------------------------------------------
5%
=
