Handbuch-KnxSmartmeter-85A-en-3.odt, 2018-10-04
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a time-diagram. Figure 3 shows one possible visualization of energy consumption in a chart on
the web server of Enertex EibPC.
Finally it should be explained on the basis of this example, as the already existing current
counter of Figure 4 can be synchronized with the Smartmeter. For this purpose the counter
value from the existing current counter shall be entered on the register “Active energy counter
(balance) - three-phase”. This can be performed using the ETS. Thereby the “Writing”-flag of the
group object “Active energy counter (balance) - three-phase” has to be set. After the group
object has been linked to a group address the application must be re-recorded. Now the counter
value of the existing current counter can be written to the corresponding group address in the
ETS group monitor. It should be noted that the value has previously to be converted from kWh
into Wh. If necessary, the “Writing”-flag of the corresponding group object can then be removed
again.
Example 2:
Bidirectional Counter for
Photovoltaics
In the second example the use of the Smartmeter as a bidirectional counter for a residential
building with a PV-system will be demonstrated. The daily energy costs and the daily tariff for the
PV-system are to be displayed on the bus. Thus, the energy costs and energy yields can be
visualized, for example, over the last 6 months on a chart. In addition the progress of the energy
fed by PV, the progress of the energy provided by the network and the balance of both are to be
visualized over the last 24 hours.
Furthermore it is shown in this example, as a simple load management can be implemented
using a single threshold. The load management shall contribute to the energy generated in the
PV-system is preferably used to supply their own consumer loads rather than feeding into the
net (for a relatively low feed-in rate).
In this example the following topics are treated: bidirectional counter, tariff counter, intermediate
counter and limit values.
The installation of the Smartmeter in this example is 3-phase in the main connection of the grid.
In general the current sensors are installed downstream the current counter of the energy
supplier. Likewise, the voltage can be measured directly downstream the current counter:
KNX-BUS
Visualization
Current
Voltage
Mains
power supply
Consumer
Smartmeter
Current Counter
(vom Supplier)
Photovoltaic
system
Figure 12: Connection of the Smartmeter in a residential building with PV-system
The example is irrespective of whether the PV-system is connected to the network single phase
or three phase.
Below is shown which relevant parameters are to set in the ETS relating to this example.
In the tab “General” the parameter “Request time and date after bus voltage recovery” should be
set. Otherwise the default values can be used:
Enertex
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