Aplc And Dplc Services - ABB ETL600 Instruction Manual

ETL600
For increased capacity and for redundancy, several PLC links can be
operated in distinct frequency bands over the same power line, sharing
the coupling devices.
The standard high frequency power output of the basic ETL600 unit is
40 W. This is for most cases adequate to ensure the required
transmission quality. For severe operating conditions with high
attenuation or high noise levels - e.g. on Extra High Voltage lines - the
output can be raised to 80 W by connecting a second power
equipment in parallel with the first. Redundancy is obtained by
coupling the two output amplifiers via an RF combiner and supplying
each from an independent power source. Two types of equipment are
thus distinguished:
•
ETL640: 40 W terminal,
•
ETL680: 80 W terminal.
For lines with low attenuation and low noise levels, the output power of
both types may be decreased to 20 W, 10 W or lower.
Power line carriers are used in almost all the countries of the world to
transfer information via HV transmission lines and has become an
important instrument for the management and safety of electrical
power systems. Of the possible PLC techniques, single sideband
modulation with a 4 kHz spacing makes the best use of the available
frequency bands and transmitting powers. This PLC technique has
become widely used in Europe, mainly for reasons of cost and its
capability of providing channels capable to carry speech, data and
teleprotection signals simultaneously. International recommendations
for the characteristics of line traps, coupling capacitors, PLC coupling
devices and single sideband PLC equipment (IEC Publications 60353,
60358, 60481 and 60495) and also for the design of PLC links (IEC
Publication 60663) have come into force. All the relevant CCIR and
ITU-T recommendations in IEC Publication 60495 were taken into
account. This ensures reliable coupling of channels at the Audio
Frequency (subsequently = AF) interfaces in power system control
centres, power stations and transformer stations between power utility
PLC, normal radio, point-to-point radio and leased back-up links.
3.1.1.

APLC and DPLC services

Around the year 1990, digital PLC (DPLC) equipment using highly
bandwidth efficient modulation techniques appeared on the market.
Compared to traditional analog PLC (APLC), DPLC offers a number of
advantages:
Enhanced transmission capacity for a given bandwidth
•
data channels running at a higher rate,
•
more speech channels.
Easy integration of the PLC network into a larger digital network
•
64 kbps channel as a tributary channel of a digital telecom
network,
Structure and Function
1KHW001489-EN
November 2005
ABB Switzerland Ltd
3-3