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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

HF Coupling modes Phase-to-Ground Inter circuit Phase-to-Phase Cc 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

Function of PLCC terminal AF 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

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

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

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 : 3780 + 30 Hz Receiver RF sensitivity : - 24 dBm Receiver Selectivity : 70dB ( 300Hz from band limit) Receiver Image rejection > 80 dB Receiver IF rejection > 80 dB PLCC OVERVIEW/P.R.MEKAP

Typical PLCC Installation F 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

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

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

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

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

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

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