Power line carrier communication (plcc)

1. Power Line Carrier Communication (PLCC) Submitted By: Er. Vishwesh Kumar Sharma

2. 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.

3. Power Line Carrier Communication System RF carrier (40-500kHz ) Power Line ( 50Hz) C.C RTU PLCC TERMINAL Transmission line L.T PAX (ABB- ETL41 )

4. Coupling Scheme Local substation To remote substation Coupling Capacitor 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

5. 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)

6. Line Trap function = PLC signal Blocking Substation Line Trap = High Impedance for PLC signal Low Impedance for Power energy Power energy PLC Signal

7. Line Trap is a parallel LC circuit Inductance of main Coil Lightning Arrester Series resistance Tuning Capacitor

8. Line Traps Mounting Options Vertical Pedestal Horizontal Pedestal Suspension

9. 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

10. PLCC Panel ( type: ABB ETL 41/42) Cabinet Module

11. 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

12. PLCC Panel Tx Block

13. PLCC Panel Rx Block

14. Types of Coupling (A) Phase to Ground coupling :-

15. Types of Coupling (B) Phase to Phase coupling :-

16. Types of Coupling (C) Inter Line coupling :- CC

17. Typical PLCC Installation MS = Master station PAX = Private automatic exchange PR = Protection relay PC = Computer M = Modem L T L T C F A X F A X PR PC MS PAX FAX M PR PC RTU FAX M PR= Protection relay FAX = Facsimile equipment M = Modem RTU = Remote terminal unit cc cc

18. 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.

19. 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.

20. 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.

21. 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.

22. THANK YOU

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