Power Line Carrier Communication (PLCC)

Submitted By:Er. Vishwesh Kumar Sharma

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.

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.

Power Line Carrier Communication System

RF carrier(40-500kHz)

Power Line (50Hz)

C.C

RTU

PLCC TERMINAL Transmission line

L.T

PAX

(ABB-ETL41)

Coupling Scheme

Local substation

To

remote

substatio

n

CouplingCapacitor

Line Matching

Unit

PLC terminal

Coaxial

•Transformer(s)•BusBar

Line Trap

The PLC signal is routed to H.V Line

The PLC signal is not absorbed by the substation

Components

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 (C.C) = Couples high frequency carrier with Power Line ( 4000

to10000pF)

Line Trap (L.T) = Do 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)

Line Trap function = PLC signal Blocking

Substation

Line Trap = High Impedance for PLC signal Low Impedance for Power energy

Power energy

PLC Signal

Line Trap is a parallel LC circuit

Inductanceof

main Coil

LightningArrester

Seriesresistance

Tuning Capacitor

Line Traps Mounting Options

Vertical Pedestal Horizontal Pedestal Suspension

LMU function

LMU = impedance matching Transformer + high voltage Protection

To prevent dangerous potential on the PLCC connection

To match PLCC set & transmission Line

Matching + Protection

LMU

PLCC Panel ( type: ABB ETL 41/42)

Cabinet

Module

ABB PLCC terminal ETL- 41 System data -- complies to IEC 495 Operating mode : Single side band Suppressed carrier

Frequency range: 40 to 500kHz (programmable in 4 kHz Steps)

AF Bandwidth: 4 kHz (Speech band=300 – 3400 Hz)

Transmitter RF output power : 40W ( +46 dBm)

Receiver Selectivity : 70dB ( 300Hz from band limit)

Receiver Image rejection > 80 dB

PLCC Panel Tx Block

PLCC Panel Rx Block

Types of Coupling

(A) Phase to Ground coupling :-

Types of Coupling

(B) Phase to Phase coupling :-

Types of Coupling

(C) Inter Line coupling :-

CC

Typical PLCC Installation

MS = Master stationPAX = Private automatic exchangePR = Protection relayPC = ComputerM = Modem

ETLETL

LTLT

CFAX

FAX

PR PC MS PAX FAX

M

PR PC RTU FAX

M

PR= Protection relayFAX = Facsimile equipmentM = ModemRTU = Remote terminal unit

cc cc

Batteries

• PLCC work on rectified AC or main supply, when supply goes off, we make use of a device for proper functioning of PLCC called battery charger.

• This is the device that provide supply to the PLCC equipment for uninterrupted working.

• It provide DC to the panel by battery.

Advantages

No separate wires are needed for communication purposes, as the power lines themselves carry power as well as communication signals. Hence the cost is less.

Power lines have appreciably higher mechanical strength compared with ordinary lines. They would normally remain unaffected under the conditions, which might seriously damage telephone lines.

Power lines usually provide the shortest route between the power stations.

Advantages

Power lines have large cross-sectional area resulting in very low resistance per unit length. Consequently carrier signals suffer much less attenuation than when they travel on telephone lines of equal lengths.

Power lines are well insulated to provide only negligible leakage between conductors and ground even in adverse weather conditions

Largest spacing between conductors reduces capacitance, which results in smaller attenuation at high frequencies. The large spacing also reduces the cross talk to a considerable extent.

Disadvantages

Proper care has to be taken to guard carrier equipment and persons using them against high voltages and currents on the lines.

Noise introduced by power lines is far more than in case of telephone lines. This is due to the noise generated by discharge across insulators, switching processes.

THANK YOU

Queries ?