Handbuch-KnxSmartmeter-85A-en-3.odt, 2018-10-04
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secures at the measurement point of the Smartmeter. That means during the installation of the
Smartmeter for a 35A main fuse the reference value would be parametrized to 35A. The
reference value for the power limit is also determined by this parameter.
The reference value for a single-phase power limit is determined by the formula “Reference
current x 230”, the reference value for a three-phase power limit is determined by the formula
“Reference current x 230 x 3”. This means a parameter value of 7 would correspond to a
reference current of 35A, a single-phase reference power of 8050W and a three-phase
reference output of 24150W.
For the limit values of active and reactive power a hysteresis can also be set. This prevents a
flood of messages during a fluctuation of a measured value around the limit value (With limits
without hysteresis at most one message per second is transmitted at the bus in extreme cases).
Also the hysteresis is indicated in percent with respect to the above-mentioned reference value.
The setting of a hysteresis has the effect, that the value 1 is not transmitted to the limit value
until the measured value exceeds the value "parametrized limit value + 1/2 x parametrized
hysteresis value". Similarly, the value 0 is not transmitted until the measured value falls below
the value " parametrized limit value - 1/2 x parametrized hysteresis value".
Attention:
If negative limit values are used at the power limits then by definition the values for
the hysteresis have also to be selected to be negative. In addition it should be noted that in case
of a negative limit value the value 1 is transmitted if the measured value exceeds the limit as an
absolute value. Similarly the value of 0 is transmitted if the measures value drops below the limit
as an absolute value.
Furthermore, limit values for counters can be realized. However, this is only possible for the so-
called intermediate counter. As described in section “Intermediate Counter” an intermediate
counter has two group objects, of which the so called object "Energy counter-previous value"
always include the counter value of the last counting interval whereas the group object "Energy
counter-current value” is reset at the end of the counting interval and then again starts to count.
Within the counting interval, therefore, only the counter of the group object "Energy counter-
current value" counts. Hence the threshold is applied to this group object. Just as the object
"Energy counter-current value" also the object "Limit Message" of the intermediate counter is
reset at the end of the interval. This allows a transmission of the value 1 to the group object
"Limit message" in each count interval when a limit is exceeded, regardless of whether the limit
has been exceeded in the previous count interval.
The limits for the intermediate counters and the powers can also be changed by the bus via
corresponding group objects. Thus, a limit value, parametrized in the ETS can be overwritten by
that value, which has been transmitted to the group object. This allows, for example, the
individual setting of a limit value depending on specific conditions, for example in the daytime a
higher limit value can be used than in the night.
Recording on the SD card
Using the SD card measured data can be recorded. By the ETS the recording mode and the
recording interval can be parametrized. The recording modes are as follows:
Name
Recording parameters
Energy consumption
Over the time interval accumulated active energy for each channel and the three-
phase system (respectively active energy (balance), active energy (consumption),
active energy (generation)), over the time interval accumulated reactive energy for
the three-phase system
Current-/Voltage monitoring
Voltage, Current, THD-U and THD-I for each channel,
Number of the voltage and current peaks detected in the time interval for each
channel during the recording interval
All measured values without
harmonics
All measured values from the mode "Energy consumption" and "Current-/Voltage
monitoring" and additional unbalanced load, line frequency and zero current.
Harmonics
Harmonics of voltage and current for each channel.
By default the recording mode is set to "All measurements without harmonics". The recording
interval can be configured in steps 1min, 5min, 15min, 1h, 12h, and 24h.
After starting the application the recording to the SD-card starts. During the recording start a
new text file in csv-format is created on the SD-card, respectively. The file name is automatically
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