Communication over power lines
Narrow band transfer is the most basic form of communication over power lines and is used for remote reading of electric meters and/or the transfer of control signals for the low voltage network (230 volts). Broadband access is another variant that involves the transfer of electronic communication between the grid station and the home. Broadband access can also include the distribution of homes.
Home network/LAN is a third variant of communication over the AC power lines that is often referred to as "homeplug" or "homeplug ethernet". The equipment normally consists of small adapters ("home plugs") that are plugged into the normal electrical power outlets. Usually one of the adapters is connected to a telecommunications network while the other adapters are connected to the telecommunications port for each individual piece of user equipment.
There are different terms for these systems that use the power supply network as a transmission medium, for example:
- Power Line Communication (PLC)
- Power Line Telecommunication (PLT)
- Power Line Networking (PLN)
- 'Broadband over Power Lines (BPL)
- Homeplug ("home network")
- Homeplug ethernet
- LAN over power
It should be noted that the transitions and differences between these different terms are not always clear. For example, "PLT" in one text can mean the same as "PLC" in another text.
Narrow band systems can cause acoustic interference (droning/whistling) in equipment that is connected to the power line in the home, for example in down lights, energy saving lights, oil-fired electrical heaters, PCs and TV sets.
Broadband systems and homeplugs can cause the undesired transmission of radio signals due to the physical features of the power supply grid which is not, in principle, constructed for transmitting these types of signals. This may cause radio services not functioning as expected.
Communication over power lines is therefore a controversial technology since it causes various types of disturbances.
Nkom regulates communication over power lines in the same manner as for other technology.
The Electronic Communications Act, Regulations relating to Electromagnetic Compatibility (EMC) for Communication, and Regulations relating to EEA Requirements for Radio and Telecommunications Terminal Equipment contain requirements relating to equipment that is marketed, sold and used in Norway.
The European Commission has given the European standardisation organisations a mandate to create standards for measuring transmitted interference from communication over power lines.
EN 50065 is a harmonised standard with EMC requirements for narrow band transmission over the low-voltage network.
There have been problems reaching an agreement on a standard for broadband communication over power lines. Therefore, as of the present date, there is no harmonised standard which only applies to the measurement of transmitted interference from broadband communication over power lines. As of the present date, EN 55022 also applies to communication over power lines.
The International Electrotechnical Commission's International Special Committee on Radio Interference, IEC CISPR, attempted to prepare an addendum for communication over power lines for a global EMC standard for information technology and communications equipment (CISPR 22). This work was stopped because of failure to reach an agreement by the time the mandate's deadline expired.
European requirements and recommendations
Communication over power lines must satisfy the requirements in the EMC Directive "Directive 2004/108/EC of the European Parliament and of the Council of 3 May 1989 on the approximation of laws of the Member States relating to electromagnetic compatibility and repealing Directive 89/336/EEC)”.
The European Commission has issued a recommendation - "Commission Recommendation on broadband electronic communications through powerlines – 2005/292/EC” The purpose of the document has been to establish harmonised, regulatory treatment of PLC systems and to equate, for regulatory purposes, these systems with traditional telecommunications systems. The document does not contain technical requirements for PLC systems. For handling of interference problems reference is made to Article 10 of the EMC Directive (2004/108/EC), cf. Section 15 of the EMC Regulations.
The European Conference of Postal and Telecommunications Administrations (CEPT) has issued "ECC Recommendation (05)04 Criteria for the assessment of radio interferences caused by radiated disturbances from wire line telecommunication networks”. The document contains recommended limits for radiation from electronic communications networks.
PLC has also been addressed by CEPT WG SE (Working Group Spectrum Engineering). This work resulted in the 2003 report: ECC Report 24 ”PLT, DSL, Cable Communications (including Cable TV), LANs and their effect on Radio Services”.
The latter two documents can be downloaded from http://www.ero.dk/.
The International Telecommunication Union (ITU) has published ITU-T recommendation K.60 "Emission limits and test methods for telecommunication networks". The recommendation applies to all networks that transmit telecommunications, including Cable TV networks, and is intended for use in connection with interference complaints. The limits are comparatively high compared with proposals in other documents. Among other things, the limits are higher than the limits in ECC Recommendation (05)04.
Complaints may be made to the Nkom if there are interference problems relating to communication over power lines.
The Nkom prefers that the involved parties cooperate to identify and implement acceptable solutions.