Example two – National Instruments NI 9478 User Manual
Page 17
© National Instruments Corp.
17
NI 9478 Operating Instructions and Specifications
Example Two
You are driving a load with 2.0 meters of cable through a cycle in
which the NI 9478 first is constantly on and passing 3 A of current
for 0.25 seconds, then drives the load at 20 kHz with 1.25 A current
for 1.25 seconds, then drives the load off for 4 seconds. While the
NI 9478 is constantly on, the output frequency is 0 kHz and the
channel uses 36% (4%
× 3
2
) of the total power budget.
shows that while the NI 9478 is driving at 20 kHz, the channel
uses 14.8% of the total power budget. While the NI 9478 is off, the
channel uses 0% of the power budget. The average percentage of
total allowable power over the complete 5.5 second cycle is 5%,
as shown in the following equation.
36% 0.25s
(
) 14.8% 1.25 s
(
) 0% 4s
( )
+
+
5.5s
-------------------------------------------------------------------------------------------------
5%
=