XT2640 Operating Manual
13 July 2016
Page 64 of 187
Recommendations:
For viewing repetitive signals. Either the DC (rising edge) or DC (falling edge) selections should be made.
For viewing a current inrush or startup event. The ABS(DC) selection should be made.
For viewing fast transients. The HF selection should be made.
Pressing the LEVEL button allows you to select the trigger detection level in the units of the signal.
For the ABS(DC) or HF trigger types only positive values can be used and you should not enter a trigger level of zero, as the
signal will always trigger.
Pressing the POSITION button allows you to set where the trigger position is located on the unzoomed chart.
You may select 0%, 25%, 50% or 75%.
Pressing the TIMEBASE button allows you to select the timebase in units of time per division similarly to an oscilloscope.
Timebase settings between 5us and 20s per division are available.
Pressing the CAPTURE MODE button allows you to choose whether the scope capture will be performed normally (NORMAL setting)
or performed for inrush capture (INRUSH setting). When configured for the INRUSH setting the following changes are made –
While a capture is being performed all D current option channels which are unscaled have the HI current range forced.
After capture of the scope trace this is released back to the configured current range.
While a capture is being performed any BANDWIDTH setting in the MEAS CONFIG screen is ignored and the captured
signal will not be bandwidth limited by that setting. After capture of the scope trace this is released back to the configured
setting.
After a capture is obtained the cursor is automatically turned on and positioned at the maximum signal of trace 1. This
enables direct readout of the maximum inrush current (for example).
Recommendation:
The INRUSH capture mode is recommended for performing inrush current measurements. This enables the use
of the optimal MEAS CONFIG settings for normal power measurements while still allowing accurate measurement
of inrush currents. Although this can be used with continuous triggering, this is primarily intended for use with
single triggered captures. The example configuration shown above shows a typical configuration for inrush
current capture, with trace 1 configured as showing the current signal. See also section 14 for full details
regarding inrush measurement and capture.
12.10.2.2
CONFIGURING
TRACES
This is performed by pressing the TRACES button. An example of the screen which allows configuration of the traces is shown
below. Changing traces does not clear any previously made scope capture; it only affects how it is displayed.
All traces must be in channels configured in the same VPA as that in which the trigger source channel is configured. If a VPA is
configured to a LF/PERIOD setting of another VPA then selecting either VPA will allow the signals in either VPA to be selected.
For each trace–
Pressing the SHOW button toggles the trace on/off. The button is highlighted colored green when enabled.
Change the color by pressing the COLOR button until the adjacent trace number shows the desired color.
There are two buttons to the right of the COLOR button which allows you to select the channel and signal to trace. Either
the voltage or current or watts signals or the inter‐phase voltage signals may be traced. The watts signal is the result of
multiplying the voltage and current signals.
The button in the /DIV column allows you to set the scaling in the units of the selected signal. Note that this is entered per
division and there are a total of 6 vertical divisions in the chart (3 above and 3 below the centerline). This can also be
automatically set to the best 1/2/5 values to show all traces within the extents of the chart when the AUTOSCALE button is
pressed on the CYCLE VIEW screen.
The button in the OFFSET column allows you to set the signal level which will correspond to the centerline of the chart.
Traces are drawn in numerical order, trace 1 first, and then trace 2, and so on. So the highest numbered enabled trace is the
uppermost trace if traces overlap.
