Review of EMC Mains a Spects in Fast PLC Including Some History

Due to recent deregulations in the EU utility market, it appears to be tempting to compete with classical telecom providers now also over utility owned power lines in the LV mains grid e.g. for broadband internet access in mostly residential areas. PLC (power line communications, sometimes called PL-T standing for telecommunications) uses unshielded, 230 V/50 Hz low voltage distribution cables inside and outside of buildings as transmission medium up to Mbit/s data rates. This requires mains injected radio frequency levels (e.g. total power < 1W, spectral power e.g. -40dBm/Hz, 1-30 MHz) that are EMC critical, with common mode currents on wirers e.g. 20dBuA at 1MHz. Such signals are normally injected at the distribution transformer. Aside from the growing international standards making effort, there are today(11/02) applicable German regulations in place (RegTP, NB 30- 07/01), controlling radiated emissions below 30 MHz, in the short wave user spectrum. Most Standards give field strength limitations only above 30MHz. In contrast to PLC, other competing broadband services like x-DSL and cable TV use well engineered, symmetrical telecom line with less disturbance potential. Regulations and standards are supposed to protect, among others, sensitive monitoring/communication services in both military and government. The latest PLC developments with all pro and cons are analyzed, computer simulations discussed and compared to many collected EMC critical (e.g. 20-40 dB over NB30 limits) measurement results. From now EU-wide available, real wide-spread PLC systems in field trials, first conclusions can be drawn. Some aspects of the EU mandate M313 regarding telecom networks will also be discussed. A review of the current state of PLC and related wire broadband technologies, with the focus on Europe, will be presented. Included are sky wave propagation issues, man made noise floor and also VHF-leakage of CTV-systems into air traffic control frequencies in Germany.