1. PLCC OVERVIEW :PRESENTED BY BIMAL NANDA
Prepared By :
PLCC OVERVIEW/P.R.MEKAP

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.
PLCC OVERVIEW/P.R.MEKAP

3. Power Line Carrier Communication SystemLT
Power Line
(50Hz) CC
RF carrier
(40-500kHz)
PAX
RTU
PLCC TERMINAL
Transmission line
(AB-ETL41)
PLCC OVERVIEW/P.R.MEKAP

4. Line diagram display Sub-Station Single Line digm bay-1 To other S/S
Line Isolator
Circuit Breaker
Bus Bar #1
Bus Bar #2
Bus Isolator 2
Bus Isolator 1
Single Line digm
PLCC OVERVIEW/P.R.MEKAP

5. H.V Line
Line Trap
Coupling
capacitor
Components
PLCC terminal
LMU
Coaxial cable
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 = 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)
PLCC OVERVIEW/P.R.MEKAP

6. Coupling Scheme Behind Front
To remote substation
Line Trap
Coupling
Capacitor
The PLC signal is routed to H.V Line
The PLC signal is not absorbed by the substation
Line Matching
Unit
Transformer(s)
BusBar
Coaxial
Local substation
PLC terminal
PLCC OVERVIEW/P.R.MEKAP

7. Line trap function = PLC signal Blocking HV Line Substation
Power energy
PLC Signal
Substation
Line Trap = High Impedance for PLC signal
Low Impedance for Power energy
PLCC OVERVIEW/P.R.MEKAP

8. Line Trap Components Corona ring Lifting lug Terminal Main coil
Tuning device
Pedestal
Protective device
Tie rod
PLCC OVERVIEW/P.R.MEKAP

9. Line Trap is a parallel LC circuit
Inductance of
main Coil
Series
resistance
Lightning
Arrester
Tuning
Capacitor
Damped single
Line Trap
PLCC OVERVIEW/P.R.MEKAP

10. Line Traps Mounting Options
Vertical Pedestal
Horizontal Pedestal
Suspension
PLCC OVERVIEW/P.R.MEKAP

11. CVT : CAPACITIVE VOLTAGE TRANSFORMER
PLCC OVERVIEW/P.R.MEKAP

12. LMU
Coupling
Capacitor
Line Trap
PLC
Coaxial
s/s
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 OVERVIEW/P.R.MEKAP

13. Modular Coupling Device ABB make MCD-80
PLCC OVERVIEW/P.R.MEKAP

14. 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.
PLCC OVERVIEW/P.R.MEKAP

15. LMU functional blocks HV -line Substation Line trap Coupling capacitorTx
ABB MCD 80 or
Coax cable Rx
PLC Cabinet
PLCC OVERVIEW/P.R.MEKAP

16. HF Coupling modes Phase-to-Ground Inter circuit Phase-to-PhaseCc
LMDU
LMU
PLC LT
LMU Cc LT
PLC Cc
LMDU
LMU
PLC LT
Phase-to-Ground
Inter circuit
Phase-to-Phase
PLCC OVERVIEW/P.R.MEKAP

17. Function of PLCC terminalAF RF IF
gain PA H A
User Signal
(0 to 4 kHz)
R.F Signal
(40 to 500 kHz)
Line Side
User Side
H= hybrid
Translation : User audio signals into radio Spectrum
Amplification : To compensate the line attenuation
PLCC OVERVIEW/P.R.MEKAP

18. PLCC Panel ( type: ABB ETL 41/42)
Modules
Cabinet
PLCC OVERVIEW/P.R.MEKAP

19. Multiplexing speech & data in 4 kHz raster
Programmable
speech bandwidth
Speech 3.4 kHz
Speech 3.4 kHz
Speech 2.0 kHz
plus
0.3
3.6
4.0
kHz
tele protection
(4 trip commands)
0.3
2.0
3.6
4.0
kHz
plus
Speed
Tele metering
(FSK modem)
300 Bd
Center frequency
120 Hz steps
1200 Bd
0.3
3.6
4.0
kHz
PLCC OVERVIEW/P.R.MEKAP

20. 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)
Spurious suppression > 60 dB
Pilot channel : Hz
Receiver RF sensitivity : dBm
Receiver Selectivity : 70dB ( 300Hz from band limit)
Receiver Image rejection > 80 dB
Receiver IF rejection > 80 dB
PLCC OVERVIEW/P.R.MEKAP

21. Typical PLCC InstallationF A X PR PC MS
PAX
FAX M
RTU
PR= Protection relay
FAX = Facsimile equipment
M = Modem
RTU = Remote terminal unit cc
MS = Master station
PAX = Private automatic exchange
PR = Protection relay
PC = Computer
M = Modem
PLCC OVERVIEW/P.R.MEKAP

22. Effect of bad weather on PLCC communication
Losses increase for all inclement 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 contaminats (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
PLCC OVERVIEW/P.R.MEKAP

23. RF Noise RF noise in HV line  two mains effects
Impulsive Noise = Caused by atmospheric discharges, breakers and isolator close/open operation
Corona effect = Due to sequences of pulse streams caused by arcs over conductors. It appears during positive-going half-cycle of the Line voltage (occurrance frequency for a 50Hz 3-phase system is 150 Hz)
The corona noise could be subject to considerable variations due to differences in the design parameters of the overhead line.
Other variations are possible due to the construction, altitude and age of the line
Weather effect can also be significant
PLCC OVERVIEW/P.R.MEKAP

24. Corona Noise Voltage (kV) Correction (dB) 33 - 14 132 - 4 220 400 + 4
400
+ 4
500
+ 5
Bad weather Noise
Typical average Noise on a 220 kV line
and for a 3 kHz Bandwidth
PLCC OVERVIEW/P.R.MEKAP

25. PLCC test instrument: Selective Level Meter
PLCC OVERVIEW/P.R.MEKAP

26. PLCC test instrument : Selective Level Oscillator
PLCC OVERVIEW/P.R.MEKAP

27. THANK YOU ALL
PLCC OVERVIEW/P.R.MEKAP