DigitalSTROM connects existing current lines with electrical devices and enables the implementation of regulation and control tasks. The main part of the system is a terminal installed in the electrical device and the control component with an installed circuit, the DigitalSTROM chip. DigitalSTROM has been available in Switzerland and in Germany since 2011, and nowadays it can be installed by electricians. Since 2012, DigitalSTROM has also been available in Italy, in the Netherlands, and in Austria. This system is based on a transmission method patented by Ludger Hovestadt and Wilfried Beck. The DigitalSTROM Allianz, is a non-profit organization that was founded at ETH Zurich in 2007. It works to establish this process as a global standard.Based on this technique, the established company Aizo AG markets and develops the system components.
DigitalSTROM transmits the information via the current line, without the use of other lines. This is why the system is especially suited to the further development of existing buildings. The basic principle – especially the technique of transmitting via the forward and backward channel – has been marked by many patents. The DigitalSTROM chip in the consumer assumes the characteristic of a slave. The data to be transmitted to the master modulate the chip on the line by increasing or decreasing the power of the sinusoidal voltage that acts on the connected consumer for some seconds. Other transmission systems for the current line modulate a high frequency signal on the mains voltage, with the characteristics of a carrier installation. Each bus subscriber has a globally unique ID that functions like the MAC address of a device from the Ethernet. It receives a local address from the master in a technique that is similar to the DHCP, which it can then use. DigitalSTROM uses the master/slave characteristic. The system is made up of the following three components.
–>The dSM DigitalSTROM meter is a bus master (BM) based on the principle of an accurate ammeter. A bus master for each circuit is indispensable. The master has a form for installation in the electrical distribution unit with the strength of one module. The BM dSM transmits data via the proprietary DigitalSTROM protocol via the line with the slaves in the circuit and via dS485, an extension of EIA-485 with the other dSM and with the dSS. Each dSM is assigned a circuit with several Digitalstrom devices (dSD) in it. N is transmitted, but the L-conductor is processed by the dSM. This enables current measuring and communication. In each phase, single or multiple dSMs can be added.
–>dSID DigitalSTROM identification device is a slave, whereby each dSID contains an explicit ID with a length of 96 bit. Currently, max. 128 slaves can exist at the same time in each circuit. The slave, designed as a high-voltage chip, is operated with mains voltage. Each dSID is coupled with L and N of the current. It has a size of approximately 5.3 x 4.7 mm. In the role as actor, the dSID device has at least one L-output, which is dimmed or switched by a chip. Furthermore, the dSID has a serial interface.
–>dSS DigitalSTROM server networks the individual DigitalSTROM units and provides connection to the other applications. The dSS DigitalSTROM has a shape for top-hat installation, requires a 24 V power supply unit, and has the characteristic of a module which uses the next module on the top-hat rail. The dSS transmits data via dS485 with the added dSM and via TCP/IP with other applications. The DigitalSTROM is not essential for a functioning DigitalSTROM system. Its role is rather that of a gateway or a web server for visualization. Additional add-ons also are offered, the server apps, which can expand the functionally of the server. Things for the general electrician (in order to assist the installation) also are available. The dSS stores time series that can be accessed via the network. The software for the dSS has patents. In addition to a simple variant for the members of DigitalSTROM, there is also an open source variant that can be used under a more specific license.
In 2008, Yello Strom received an award which was mainly related to the resolution of electronic counter data, but also addressed errors with regard to the planned DigitalSTROM dSID chips. Because of this clear identification, too many accurate data would be available via the connected electrical devices. Yello Strom attach value to the customer having data ownership and the customer being able to decide which information reaches the power supplier. As the server also serves as memory, this also was a reason for the decision to market the software as open source and in doing so, to create transparency.
Currently, there are no fixed prices for current alone. The first devices in which this chip is installed, (e.g. the lamp dimmer terminal) are priced at approximately 70 euro. Additional charges are made for the phase filter and a one off charge per apartment (for a Digitalstrom server (dSS) as an IP gateway). With this, DigitalSTROM still below the prices for conventional systems in terms of the total price.