There appears to be some confusion about the acronyms PLT and PLC. PLT – power line telecommunication – generally refers to the use of power reticulation to deliver broadband internet. In some parts of the world, like the USA, it is also known as BPL – broadband over power line. PLC – power line communication – is used more often in the remote control of power reticulation and developments such as smart grids and remote metering.
However the confusion remains. The Independent Communications Authority of South Africa (ICASA) calls it PLT and the University of Johannesburg insists it is PLC. I would like to suggest that PLC is used when we refer to the use of frequencies of 2 to 30 MHz and above, and below 2 MHz where the power utilities operate their controls as PLC.
At a joint meeting of four SABS technical committees held to discuss a new standard proposed for the use of PLC in controlling the electricity network, metering and the so-called smart grid applications, Eskom and some vendors objected to the ratification of South African National Standard (SANS 50065-1) as they believed that the standard did not meet all the Eskom, and possibly metro requirements to manage the electricity grid.
Eskom is seeking to use frequencies up to 500 kHz while the standard only covers applications of 3 – 148,5 kHz. Specifications between 148 and 500 kHz are yet to be co-ordinated worldwide.
The proposal to hold a joint meeting of TC73 (electromagnetic compatibility, TC74 (telecommunications) TC62 (electricity metering and load control and TC 80 (SABS/ICASA Regulatory standards) was proposed by Paul Johnson, chairman of the NRS 094 Working Group.
Eskom requested the SABS to hold the ratification of the SANS 50056-1/EN 50065, IDT,ED2 standard. Eskom’s view is that frequencies between 0 – 500 kHz, used in the low-voltage narrowband power line communication networks, should be wholly reserved for the power utility’s implementation of advanced metering infrastructure solutions, load control, appliance control and remote connection and disconnections as well as smart grid systems.
There is no agreement between various industry players. Utillabs suggested that the band between 3 kHz and 2 MHz should be considered for use of PLC.
There is currently a great deal of activity world-wide in the area of 0 – 2 MHz for use in PLC, driven by the interest in the development of smart grids for the energy distribution industry.
Landis + Gyr is of a different opinion. It believes there should be no argument against the ratification of the proposed standard and urged the SABS to adopt EN50065-1 when it is published internationally (currently a revision to the 50065-1 standard is under consideration in Europe). The company also asked that ICASA suspends issuing of type approvals for PLC equipment in the FCC band (10 – 490 kHz) and frequency up to 2 MHz until the reason for the rejection of the German application has been studied. If is transpires that the same reasons for rejection of FCC frequencies exist in South Africa, then ICASA should recall all type approvals that have been granted for such equipment.
Landis +Gyr suggests that Utilabs be asked to perform independent research into the impact of their installed ITU-T region 2 FCC type approved equipment on the existing ICASA licensed users of that spectrum. Currently in the national table of frequency allocations the range 283,5 kHz – 2 MHz is allocated to various services, amongst others aeronautical navigation, distress calling, radio location, amateur radio and broadcasting but not tor PLC.
There is also a debate as to whether PLC frequencies should be regulated as cable is the carrier and not free space. The other argument is that as long as PLC systems meet the limits of CISPR 22 (the basic international EMI standard for information technology equipment) why should ICASA become involved?
The joint meeting did not arrive at any conclusions. The various representatives were sent home with the mandate to carry out investigation into the various issues tabled. The group will convene again in June 2011.
Powerline communications in the spotlight again << Comments and views