XT2640 Operating Manual
13 July 2016
Page 97 of 187
NUM
INTERVALS
: This allows you to select that an assessment is to be performed in two or three intervals, each having an identical
test time, with the assessment being paused between intervals until you press the CONTINUE button, or to be performed as a single
interval.
Recommendation:
This is generally not required and so should be set to 1, but in EN61000‐3‐2 Annex C there are situations where this
activity is required and so should be set to 2 or 3 accordingly.
AUTO
START/STOP
: This allows you to select any activities regarding when the EUT is started or stopped (i.e. draws significant
power or draws little power). If set to other than OFF then there are additional settings available which allow you to enter the
start/stop power detection level and the delay to use following a transition between start and stop (see below for details). The
available selections are‐
OFF: When this is selected the assessment always progresses and there is no detection of whether the EUT is started or
stopped.
DELAY ONLY: When this is selected whenever the EUT power changes from above the detection level to below it (i.e. becomes
stopped) or from below to above (i.e. becomes started) then a delay is started during which the assessment is automatically
paused. This is the activity required by clause 6.2.3.3 of EN61000‐3‐2 and clause 4.2.4 of EN61000‐3‐12 when a EUT is
“
brought
into
operation
” or “
taken
out
of
operation
”.
AUTO PAUSE: When this is selected the assessment is continuously paused whenever the EUT power is below the detection
level.
AUTO STOP: When this is selected the assessment is only performed while the EUT power is above the detection level and is
automatically stopped when the EUT drops below the detection or the configured test time has elapsed (whichever occurs
first). If the EUT power is below the detection level when the assessment is started then it is paused until the EUT power goes
above the detection and then after the configured start delay has elapsed. This is rarely used, but is useful if the EUT has only
a relatively short period of operation during assessment. Typically, the TEST TIME set would be longer than the expected
operation time of the EUT for this situation.
Note:
Neither any delays nor pauses are considered part of the assessment time.
Recommendation:
Most EUTs do not actually start or stop during an assessment so OFF is generally recommended for this setting. For strict
assessment to EN61000‐3‐2 and ‐12 then DELAY ONLY or possibly AUTO STOP settings should be considered along with
entering values for the start/stop detection power level and the delay to use.
AUTO PAUSE is rarely used, but is included to allow full configuration capability, particularly when mitigation is needed for
an assessment failure.
AUTO STOP is rarely used, but is useful if the EUT has only a relatively short period of operation during assessment.
Typically, also the TEST TIME would be set slightly longer than the expected operation time of the EUT in this situation.
STOP
POWER
: This allows you to enter the start/stop detection power level and is only available if AUTO START/STOP is not set to
OFF. See above for how this setting is used.
Recommendation:
If needed this should be set to a suitable value to allow the XT2640 to reliably detect starting and stopping events in the
EUT.
START
DELAY
: This allows you to set the number of seconds to delay after the EUT is detected as starting or stopping before
continuing the assessment level and is only available if AUTO START/STOP is not set to OFF.
Recommendation:
EN61000‐3‐2 clause 6.2.3.3only allows this to be set to 10 seconds, and EN61000‐3‐12 clause 4.2.4 recommends 10
seconds but allows a longer period. The XT2640 allows any delay to be entered within the range 3 seconds to 1000
seconds.
18.4.3.4
STARTING
THE
ASSESSMENT
When the START button is pressed on this screen the assessment is started as you have configured it and you are returned to the
ASSESS EUT screen, otherwise if the CANCEL button is pressed any entries you have made are discarded and you are returned to the
ASSESS EUT screen without an assessment being started.
Recommendation:
You must ensure that the 1.5 second filtering required by the standards has fully settled prior to starting an assessment so
the EUT must have been powered and have been stable for at least 10 seconds prior to starting the assessment, the XT2640
does not enforce this and in general the EUT will require longer than this to stabilize.
For certain types of EUT the standards may have additional requirements regarding a minimum stabilizing time period
during which the supply source and EUT are powered prior to starting an assessment. Particularly see Annex C of
EN61000‐3‐2 for further details.
18.4.4
VIEWING
THE
RESULTS
OF
AN
ASSESSMENT
Both during an assessment and after an assessment has been performed the results of that assessment are displayed in the ASSESS
EUT screen.
Note:
In some cases, as described in the following sub‐sections, the data shown is specific to the selected XT2640 channel to be
viewed as selected by the leftmost button across the top of the screen.
