Power Line Communications

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PLC – Power Line Communications – also known as BPL-Broadband over Power Lines – is a rapidly
growing means of data transport. Like twisted-pair copper telephone lines
and coaxial wire CATV systems, the copper-wire electrical power grid is a
network capable of high speed data transmission. AC – Alternating Current – is
modulated at 50/60 CPS-Cycles Per Second allowing for data transmission at
higher frequencies (above 50/60 cycles/Hertz). The electric power grid
consists of many different voltages such as:

  • EHV-Extra High Voltage – 400-1,000 KV-Kilo Volts

  • HV-High Voltage – 35-400 KV
  • MV-Medium Voltage – 1-35 KV
  • LV-Low Voltage to 1 KV

Note: HV-High Voltage is defined by some as above 30 KV-KiloVolts, so this
is a general guideline, not an absolute one. As a footnote, many LAN
switches and Wi-Fi-Wireless Fidelity AP-Access Points use inline (data and
power over the same wire) VLV-Very Low Voltage at 48 VDC-Direct Current.

The Wi-Fi data signal is injected onto the MV-Medium Voltage distribution
line, where the data transmission propagates (moves) from the substation to
the customer. Data repeaters regenerate (rebuild) the signal every 2,000
feet along the MV feeder until the termination point. Each repeater is also
a Wi-Fi access point, providing access service to servers or the Internet to
any Wi-Fi device within range. This could be used for Wi-Fi-on-the-road
service along a highway. At the house transformer where voltages are stepped
down (reduced) from 13,000 or less volts to house voltages of 240/120 volts,
the data “extractor” also operates via Wi-Fi or 802.11b/g. Wi-Fi operates at
2.400-2.483 GHz up to 11 MBPS-MegaBits per Second at 100-150 feet with the
same frequencies as cordless telephones and microwave ovens.

Thomas B. Cross

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