2. PLCC is a technology which uses power lines as
physical media for data transmission
•PLCC can offer a "no new wires” solution because
the infrastructure has already been established.
•PLCCs are used for transmitting data at a rapid
speed through a power line in a house, an office, a
building, and a factory, etc.
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3. PLCC TECHNOLOGY
PLCC system uses the same High Voltage
transmission line connecting two sub-stations for
telecommunication purpose too.
PLCC is used in all power utilities as a primary
communication service to transmit speech, telemetry
and protection tripping commands. This is economic
and reliable for inter grid message transfer as well as
low bit rate RTU signals.
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4. The voice/data are mixed with radio frequency
carrier (40-500kHz), amplified to a level of 10-80W
RF power and injected in to high voltage power
line using a suitable coupling capacitor. The power
line as a rigid long conductor parallel to ground,
guides the carrier waves to travel along the
transmission line. Point to point communication
takes place between two SSB transceivers at both
ends.
Here, the existing alternating current (AC) power
wires serve as a transmission medium by which
information is relayed from a transmitter or control
station to one or more receivers or loads
connected downstream from an AC source. 4
5. • The telephone communication system cannot be
directly connected to the high voltage lines, which
is therefore done by suitably designed coupling
devices.
• These usually consist of high voltage capacitor
with polarity devices used in conjunction with
suitable line matching unit (LMU) for matching the
impedance of line to that of the coaxial cable
connecting the unit to the PLC transmit-receive
equipment.
5
6. H.V Line
Line
COMPONENTS Trap
Coupling
capacitor
Coaxial
cable LMU
PLCC
terminal
PLCC TERMINAL - Translates voice and data into High Frequency Carrier. Output
Power =10 to 80W.
LMU - Line Matching Unit , for impedance matching between line
and coaxial cable, includes high voltage protection devices
like drainage coil(20mH), lightening arrestor(500V) and an earth switch.
COUPLING CAPACITOR - Couples high frequency carrier with Power Line
( 4000 to10000pF)
LINE TRAP - Does not allow the transmitted HF carrier to enter inside the sub-
station. (L = 0.5 to 2mH) With out Line trap HF carrier get by-passed to some
other line on the same bus bar and may leak to ground ( a earth switch inside
the yard provided for each bay is kept closed during maintenance) .
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7. COMPONENTS
Behind Front
Line Trap To remote
substation
Coupling The PLC
Capacitor
signal is
routed to
Line H.V Line
•Transformer(s) Matching
•BusBar Unit
The PLC
signal is
not
Coaxial
absorbed
by the
Local substation substation
PLC terminal
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8. Line trap function = PLC signal Blocking
HV Line
Power energy
PLC Signal
Substation
Line Trap = 1. High Impedance for PLC signal
2. Low Impedance for Power energy
10. LINE MATCHING
UNIT FUNCTION Line Trap
LMU =
Coupling
impedance matching Transformer s/s Capacitor
+ high voltage Protection LMU PLC
Coaxial
To prevent dangerous potential on
the PLCC connection
To match PLCC set & transmission Line
Matching + Protection
LMU
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11. Elements of Coupling Device
• Drain coil for draining of HV leakage currents to earth.
• Lightning arrester at the line terminals of coupling device for
transients protection
• Transformer for impedance matching and galvanic isolation between
line and PLCC terminal.
• Earth switch for grounding of line terminals during maintenance.
• High-pass or band-pass filter elements for efficient matching.
• connectivity to equipment room through coaxial cable.
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12. The PLCC Modem is in the form of a ready-
to-go circuit module, which is capable of
transferring data over the power cable at
the low voltage end of the power transformer
of a 3-phase/ 4-wire distribution network.
A pair of Embedded PLCC Modems connected
on the power line can provide low speed bi-
directional data communication at a baud
rate of 9600 bps.
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14. Communication Interface
The Communication Interface provides serial
communication between the Embedded PLCC Board
and a PC.
The board uses a standard RS-232/UART port for
communication with a COM port on a PC. In Case
on board RS-232 level translator is not needed a
TTL interface is also provided. It can be used with,
for example, a PC running a terminal program such
as Hyperterminal for use under Windows
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17. TECHNOLOGY
The Embedded PLCC modem is based on the Differential Code Shift Keying
(DCSK) Technology. This technology in Power Line Carrier (PLCC)
communication is well known for its high immunity to electrical noise
persistent in the power line. Other suppliers use narrow band modulation,
which are sensitive against single tone noise sources. The external Analogue
front end (AFE) ensures high line drivability even at low impedances. The
Embedded PLCC modem has many mechanisms to make the communication
more robust.
These are built-in hardware features such as:
• FEC (Forward Error Correction)
• CSMA/CA (Carrier Sense Multiple Access / Carrier Avoidance)
• LQI (Line Quality Indication)
• Three Different communication modes
Standard Mode, Robust Mode,Extremely Robust Mode)
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18. Typical PLCC Installation
LT LT
cc cc
C FX
A
ETL ETL
FX
A
M M
PR PC MS PAX FAX PR PC RTU FAX
LT= Line Trap
MS = Master station CC = Coupler Capacitor
PAX = Private automatic exchange PR= Protection relay
PR = Protection relay FAX = Facsimile equipment
PC = Computer M = Modem
M = Modem RTU = Remote terminal unit
20. DUAL STREET LIGHT
CONTROLLER NODE
The above schematic is a typical dual street light controller node.
Each such node can monitor and control two street lights at a
time.
● The IO control can turn ON/OFF each light independently.
● The sensor and IO control unit can detect ON/OFF status of
each streetlight and can also detect burn out condition of each
light as well.
● This has an ambiance light sensor for autonomous operation.
With this feature, the street light can be automatically turned ON
if the surrounding light intensity goes below a preset threshold.
Similarly, the light can be turned OFF, if ambiance light detected is
higher than a preset threshold.
● This can measure the amount of energy consumed by each of
the lights so as to report to the central station its energy usage.
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21. Power line Node
The nodes are the modules which are fixed in the street lights.
The central station essentially speaks to this node, via the
concentrator, for its application. The system has the following
architecture.
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22. AUTOMATIC METER READING
The need of AMR :
The distributor must be capable of connecting the customers, getting the reading
from their meter, and to disconnect them if necessary. This will enable him to know
the amount of energy each customer uses and this can be compares with the total
consumption. If a customer is not paying the bill, the office personnel can disconnect
him with a single command. When he clears the dues, the connection can be re-
established from the office itself. The disconnection- re connection can be
programmed, eliminating the human effort required and also, making it corruption
free. The server at the office is getting all the customer’s reading and thus the billing
process can be automated. The different systems of the AMR are:
• Telemetry
• Wireless communication
• Communication through Optical cables
• Communications using the power lines 22
23. AUTOMATIC METER READING
In the Power Line Carrier Communications, the
remote metering unit is capable of receiving and
decoding the communication signals, and to respond
accordingly. If the meter can be controlled from the
distributors’ office, almost all types of thefts can be
prevented and the power quality can be assured at
the consumer premises. The use of power line
carrier communication minimizes the amount of
capital required for the infrastructure. The existing
system can be converted to the new system with the
introduction of certain components.
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25. Embedded PLCC modem hardware is used for both PLCC Master
device and nodes (Slave device). A 3 pin jumper setting is provided on
the board, connecting the jumper to pin 1 and pin 2 configure the
device as Master ( concentrator ) while connecting it to pin 2 and 3
configure the device as node.
5-2 Setting Up the User Interface
The demo requires a minimum two PCs with Microsoft® XP® OS. On
one PC, PLCC Master emulation code runs and sends data to
Embedded PLCC modem (Master device) via RS232 interface which in
turn sends data over power lines to node device connected to another
PC via RS232 interface running node emulation code.
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28. ADVANTAGES OF PLCC
• No separate wires are needed for communication
purpose.
• Both communication and power transfer can be
possible on same circuit.
• Power lines provides the shortest route between the
power station.
• Higher mechanical strength.
• Increased reliability.
• Lower attenuation over long distance.
• Implementation cost is reduced.
29. EFFECT OF BAD WEATHER
ON PLCC COMMUNICATION
Losses increase for all severe weather conditions
The worst offender is when heavy frost is formed on the line
Because of the skin effect, the carrier signal tries to propagate
on the ice instead of the conductor.
The attenuation can change as much as 4:1 depending on the
frequency.
The contaminants (on the insulators) have a larger effect when it is
raining than when the line is dry.
The worst condition is a light rain with the presence of contaminants
on the insulators
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30. Typical applications of PLCC are
•Street light control,
•Automatic Meter Reading,
•HVAC control,
•Low Speed Data Networks,
•Signs and Information Display,
• Fire and Security Alarm etc.
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