Power Line Communication

The PLC (power line communication) designates a technology that uses the medium and low voltage electrical network to provide telecommunication services. Although, since its first applications when the frequency range started at a low level, power line communication is today more commonly used for high-frequency applications, also known as broadband power line (BPL). The electrical network has been used for a long time by producers and distribu­tors of electrical power for the purpose of network monitoring and remote control at low speed. Nowadays, an electricity producer or distributor cannot ignore standardiza­tion. It is interesting to note that the deployment of electrical networks, their inter­connection, and the ever increasing number of electrical appliances have resulted in the emergence of the first network standardization bodies such as the IEC (Interna­tional Electrotechnical Commission).

PLC Technologies

The principle behind the power line communication technique is not one that has emerged recently. In 1838, Englishman Edward Davy proposed a solution allowing remote measure­ments to be taken of battery levels of sites far from the telegraph system between London and Liverpool. In 1897, he submitted the first patent (British Patent No. 24833) for a technique for the remote measurement of electrical network meters communicating over electrical wiring. In 1950, the first PLC systems, known as Ripple Control, were designed and then deployed over medium- and low-voltage electrical networks. The carrier fre­quency was then between 100 Hz and 1 kHz. It was necessary to establish sin­gle-directional communications via control signals for the remote switching on and off of public lights or for tariff changes. The first industrial systems named Pulsadis appeared in France in 1960. The power involved was approximately a hundred kilovolramperes (kVA).

Then the first CENELEC band power line communication systems appeared, extending from 3 to 148.5 kHz, and allowing bidirectional communications over the LV (low voltage) electrical network, for instance, for meter readings (remote meter readings) as well as for a great number of applications relating to the home automation field (intruder alarm, fire detection, gas leak detection, and so forth). Much less power needed to be injected, since the power was reduced to levels of approximately a hun­dred milliwatts.

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