XT2640 Operating Manual
13 July 2016
Page 82 of 187
17
PERFORMING
EN50564
LOW
POWER
MEASUREMENTS
The STBY POWER Screen gives you the ability to configure, start/stop, and view the results of low power measurements in
accordance with EN50564:2011.
It is assumed in this section that you are conversant with the general operating methods used in the XT2640 as described in section
12.
The STBY POWER screen can be selected for view from any of the Main Data Screens by pressing the STBY POWER button.
The XT2640 has the ability to perform low power measurements independently in each VPA, so a single XT2640 can perform up to 3
independent low power measurements. You select which VPA is being configured, controlled and viewed by using the VPA button
(the leftmost across the top of the screen).
The XT2640 performs the low power measurement in accordance with EN50564:2011 para. 5.3.2, which is the recommended
method for all low power measurements.
If you prefer a measurement according to EN50564:2011 para. 5.3.3 (“
Average
reading
method
”) or 5.3.4 (“
Direct
meter
reading
method
”) then these can be accommodated using the POWER DATA screen with the VPA properly configured and (as needed) using
the Integration capabilities of the XT2640 described elsewhere in this document. The STBY POWER screen should generally not be
used for these methods, but you should note that the method employed in the STBY POWER screen to EN50564:2011 5.3.2 is “
the
recommended
approach
” and “
should
always
be
used
if
there
is
any
doubt
regarding
the
behavior
of
the
product
or
stability
of
the
mode
”.
Note:
The word “
sampling
” in EN50564:2011 relates to sampling of the individual measurement period results of the XT2640,
not to the sampling of the signals used to perform each such measurement.
17.1.1
VPA
MEASUREMENT
CONFIGURATION
FOR
EN50564:2011
MEASUREMENTS
There are some settings in the MEAS CONFIG screen which the user should ensure are appropriate for performing EN50564:2011
compliant measurements. These are not enforced by the XT2640 to allow you more flexibility in using this type of measurement.
All settings on the MEAS CONFIG screen which are not listed here do not affect how low power measurements are performed to
EN50564:2011.
Note:
The RESPONSE configuration setting for the VPA is not applied to the STBY POWER results.
The COUPLING configuration setting for the VPA is not applied to the STBY POWER results (all STBY POWER results use
AC+DC coupling as required by EN50564:2011).
Although allowed by the XT2640, it is not recommended to reconfigure a VPA during a low power measurement.
The MEAS CONFIG screen shown below gives an example of a fully EN50564:2011 compliant configuration of the XT2640 when the
power source and load are connected via a LPA‐1 accessory.
