17-12
IM DLM3054-01EN
Measuring Inrush Current by Computing the Joule Integral (I
2
t)
Measure the Joule integral (I
2
t) of the inrush current. This feature is useful when you are evaluating and
comparing items such as device fuses.
When you select I
2
t, you can display measured values and a waveform of the Joule integral and compute
statistics.
T: Measurement time period
i(t): Sampled current data
T
0
i(t)
2
dt
Joule integral I2t [A2s] =
Probe Setup (ProbeSetup)
The channel selection, probe attenuation, voltage-to-current conversion ratio, and deskew settings are the same
as those for the switching loss analysis feature.
Measurement Setup (Measure Setup)
Measurement Item (Item)
OFF: The Joule integral measured values are not displayed.
I
2
t: The Joule integral measured values are displayed.
You can display a total of up to 30 Joule integral measurement items and automatically measured waveform
parameter items. If measured Joule integral values are not displayed, reduce the number of automatically
measured waveform parameter items.
Source Window (Time Range)
Specify the range over which to measure the Joule integral by selecting one of the following windows.
Main: Entire main window
Zoom1: Entire Zoom1 window
Zoom2: Entire Zoom2 window
Measurement Time Period (T Range1/T Range2)
Set the measurement time period in the source window.
The measurement range when power analysis I
2
t is specified is shared with the measurement range that is
specified for the normal automated measurement of waveform parameters (Area1).
Displaying Measured Results
When measurement results are displayed on the screen, symbols that indicate the measurement item and
measurement channel are shown in front of the measured values as shown below.
Example
I
2
t(C2)
I
2
t: Joule integral
C2: Current channel
17 Power Supply Analysis Feature (Power Analysis and Power Measurement, Option)