PLCC SYSTEM by P R MEKAP GRIDCO POWER

PLCC SYSTEM by P. R. MEKAP GRIDCO POWER TRAINING CENTRE “PLCC system” presented by P R Mekap (Tel) SLDC Asst. Engineer SLDC, BBSR 1

Part -I Overview of PLCC Systems “PLCC system” presented by P R Mekap (Tel) SLDC 2

Typical PLCC Installation WT WT cc cc C FAX M M PR PC MS = Master station PAX = Private automatic exchange PR = Protection relay PC = Computer M = Modem MS PAX FAX PR PC RTU FAX PR= Protection relay FAX = Facsimile equipment M = Modem RTU = Remote terminal unit “PLCC system” presented by P R Mekap (Tel) SLDC 3

Topics to be discussed 1. Why PLCC is preferred in by Power Utilities? 2. What is the RF power and frequency band in PLCC? 3. Typical PLCC installation; how speech, data and protection commands are transmitted over PLCC system ? 4. PLCC link design, factors affecting performance of a PLCC link, effect of corona noise in PLCC. 5. Features of digital PLCC. “PLCC system” presented by P R Mekap (Tel) SLDC 4

System description Ø PLCC is used in all power utilities as a primary communication service to transmit speech, telemetry and protection tripping commands. Ø PLCC system uses the HV power transmission line of the utility as a metallic medium for telecommunication. No need for laying separate telephone lines on the electric poles or hire lease lines from public telephone companies. Ø This is very economic, dependable and secure communication compared to any other means like HF wireless, VSAT or lease line. Cheaper than microwave radio and optical fibre. PLCC communication is feasible for line length up to 800 k. M. “PLCC system” presented by P R Mekap (Tel) SLDC 5

Ø The frequency band used for PLCC is 90 - 500 k. Hz. Type of modulation adopted is SSB-SC as per IEC-495 specification. PLCC channel carrying voice and super imposed data has gross band width of 4 k. Hz. Ø RF out power of a PLCC transmitter is 20/40/80 W depending on distance. The radio frequencies used by the power utilities for PLCC should be approved by WPC, New Delhi, Ministry of Communication Govt. of India. Government charges a licence fee for this communication too. Ø The RF out put of PLCC terminal is injected in to high voltage power line using a suitable high voltage HF coupling capacitor(4 -10 n. F). Also HF traps ( 0. 2 – 2 m. H) are inserted at both ends of the line. “PLCC system” presented by P R Mekap (Tel) SLDC 6

H. V Line Wave Trap Coupling apacitor Components of PLCC Terminal Translates voice and data into Radio Freq. Carrier. Coaxial cable “PLCC system” presented by P R Mekap (Tel) SLDC LMU 7

POWER FREQUENCY & CARRIER FREQUENCY WT Power Line (50 Hz) CC RF carrier (40 -500 k. Hz) PAX RTU PLCC TERMINAL Transmission line (ABB-ETL 41) “PLCC system” presented by P R Mekap (Tel) SLDC 8

Function of PLCC terminal IF AF IF IF User Signal (0 to 4 k. Hz) RF (40 to 500 k. Hz) H H AF RF A User Side R. F Signal PA IF AF IF gain RF IF Line Side Frequency conversion : audio signals into radio spectrum and vice versa Amplification : Sufficient RF power to compensate the line attenuation “PLCC system” presented by P R Mekap (Tel) SLDC 9

Wave Trap function 40 - 500 k. Hz ( HF) : Blocked WAVE Trap Behind Coupling Capacitor • Transformer(s) • Bus. Bar Front Line Matching Unit Coaxial The carrier signal is transmitted over Power Line to reach the opposite end The carrier signal is blocked by line trap; not allowed to enter inside the switch- yard PLC terminal “PLCC system” presented by P R Mekap (Tel) SLDC 10

Wave trap function 50 Hz (Power Freq): through pass HV Line Power energy PLC Signal Substation Line Trap = High Impedance for PLC signal Low Impedance for Power energy “PLCC system” presented by P R Mekap (Tel) SLDC 11

Wave Traps Mounting Options Vertical Pedestal Horizontal Pedestal “PLCC system” presented by P R Mekap (Tel) SLDC Suspension 12

Wave Trap is a Band Stop filter (50 -500 k. Hz) Inductance of main Coil Lightning Arrester Series resistance Tuning Capacitor Damped single “PLCC system” presented by P R Mekap (Tel) SLDC Line Trap 13

Wave Trap assembly Corona ring Lifting lug Terminal Main coil Tuning device Pedestal Protective device Tie rod “PLCC system” presented by P R Mekap (Tel) SLDC 14

Capacitive Voltage Transformer ( CVT ) “PLCC system” presented by P R Mekap (Tel) SLDC 15

220 k. V CVT and HF connection 8800 pf CVT HF LMU COAXIAL CABLE DISCONNECT THIS LINK 20 m. H Drain coil PLCC TERMINAL “PLCC system” presented by P R Mekap (Tel) SLDC 16

LMU : Type-MCD-80, ABB make “PLCC system” presented by P R Mekap (Tel) SLDC 17

Co-axial Cable “PLCC system” presented by P R Mekap (Tel) SLDC 18

LMU function LMU = impedance matching + high voltage Protection Ø To prevent dangerous potential on the PLCC connection s/s LMU ØTo match impedance of PLCC set with power Line impedance. Matching + Coaxial PLCC Protection LMU “PLCC system” presented by P R Mekap (Tel) SLDC 19

LMU functional blocks HV -line Substation Wave trap PLCC Panel Coupling capacitor Tx or ABB Coax cable Rx MCD 80 “PLCC system” presented by P R Mekap (Tel) SLDC 20

ABB- MCD 80 internal wiring Coax To PLCC CVT Z 2 75ž L A E. S Z 1 Q 1 F 1 L 1 A B C D E F LE G Drain Coil K C 1 L M C 2 N O C 3 P Q C 4 R H 3 T 125ž 2 Match Trans L 2 T 1 Z 2 1 C “PLCC system” presented by P R Mekap (Tel) SLDC 21

Built in protection devices of LMU §Drainage coil to sink the leakage currents from CC/CVT to ground. §Lightning arrester across the CVT HF terminals and ground for transients protection. § Earth switch for grounding of CVT HF terminal during maintenance. §RF Transformer for galvanic isolation between power line and PLCC terminal. “PLCC system” presented by P R Mekap (Tel) SLDC 22

HF Coupling modes LT LT Cc PLC LT Cc LMU PLC LT LMDU Cc LMU LT Cc Phase-to-Ground PLC LMDU Cc LMU Inter circuit Phase-to-Phase “PLCC system” presented by P R Mekap (Tel) SLDC 23

Part -II PLCC Link Design “PLCC system” presented by P R Mekap (Tel) SLDC 24

Line loss and Noise u Signal loss factors w. Taping loss (effect of PLCC terminals in parallel) w. Coaxial cable attenuation ( length of the cable) w. Return loss ( improper line matching ) w. Coupling loss (LMU, CC, Wavetrap) w Modal coversion loss (effect of carrier current on conductors) w. Line loss (type of tower, conductor type and line length) w. Line loss (Bad Weather conditions; rain, frost) w. Corona Noise( Swicth Yard equipments & line insulators) w. White Noise ( semiconductor devices) “PLCC system” presented by P R Mekap (Tel) SLDC 25

Loss due to Parallel Working of PLCC Parallel working of several PLCC terminals results a loss of power due to loading of transmitters by each other. This depends on frequency spacing between adjacent transmitters. It is called tapping loss and it should not exceed 2 d. B. TX Spacing >12 k. Hz TX Spacing > 16 k. Hz 1 db per additional equipment 0. 5 d. B per additional equipment “PLCC system” presented by P R Mekap (Tel) SLDC 26

Co-axial cable Loss The RF power through coaxial cable gets attenuated by 2 to 6 d. B per k. M of cable length depending on carrier frequency used. Frequency (KHz) Attenuation(d. B/km) 10 100 200 1. 2 2. 5 3. 2 300 400 500 3. 9 4. 8 5. 5 “PLCC system” presented by P R Mekap (Tel) SLDC 27

Modal conversion loss Coupling Ph to Gnd Ph to Ph Inter Circuit Single circuit Line Double Circuit Line 1. 5 … 3. 5 d. B Coupling to one Circuit 1 … 3. 5 d. B 0. 5 … 1 d. B Coupling to one Circuit 0. 5 d. B --- 0 d. B While RF power is directly coupled to one or two phase conductor(s) carrier current flows on all the three or six phase conductors running parallel. Depending on coupling methods used, the magnitude and direction of carrier current in each conductor is different. In an unfavorable mode the effect is equivalent to loss of transmit power up to 3. 5 d. B = ac “PLCC system” presented by P R Mekap (Tel) SLDC 28

Carrier signal attenuation per mile of line length Attenuation in db/mile depends on conductor size, spacing above ground, transpositions, type of coupling and carrier frequency. It also varies periodically with weather conditions (rain and frost do affect) “PLCC system” presented by P R Mekap (Tel) SLDC 29

Line attenuation per Km = α It is the attenuation of transmit power over a line length of one kilo meter = α db a » 0. 071 f d. n -3. + f 10 f = frequency (k. Hz) d = diameter of phase conductor (mm) n = number of phase conductor in bundle “PLCC system” presented by P R Mekap (Tel) SLDC 30

Source of RF Noise is HV line ØCorona Noise = 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 50 Hz 3 phase system is 150 Hz) ØImpulsive Noise = Caused by atmospheric discharges, breakers and isolator close/open operation “PLCC system” presented by P R Mekap (Tel) SLDC 31

Corona Noise Bad weather Noise Voltage (k. V) Correction (d. B) 132 - 4 220 0 400 + 4 500 + 5 Typical average Noise on a 220 k. V line and for a 3 k. Hz Bandwidth “PLCC system” presented by P R Mekap (Tel) SLDC 32

Effect of bad weather on PLCC links Ø The contaminats (on the insulators) have a larger effect when it is raining than when the line is dry. Ø The worst condition is a light rain with the presence of contaminants on the insulators The worst offender is when heavy frost is formed on the line ØBecause of the skin effect, the carrier signal tries to propagate on the ice instead of the conductor. ØThe attenuation can change as much as 4: 1 depending on the frequency. “PLCC system” presented by P R Mekap (Tel) SLDC 33

Additional loss Depending upon line configuration , mode of coupling and number of transpositions an additional loss is considered = aadd Number of transpositions Coupling arragement IEC 60663 0 1 2 > 2 single circuit, Ph- Gnd Centre only ( +++) 0 6 3 to 8 - single circuit , Ph- Gnd Centre or top 0 to 3 6 to 12 single circuit, Ph- Ph Center to outer( +++) 0 to 5 8 to 12 2 to 10 - single circuit , Ph- Ph Centre to top 0 to 3 4 to 8 Double circuit, IC Centre to centre 2 to 10 Double circuit, double 0 to 1 0 to 4 2 to 8 Differential, Centre to top “PLCC system” presented by P R Mekap (Tel) SLDC 2 to 8 34

Channel Band Width and White Noise The noise power is proportional to noise band width of the channel. Noise bandwidth of 50 Baud voice frequency telegraphy channel is taken to be 80 Hz and speech has band width of 2100 Hz (300 Hz-2400 Hz) Noise power in a 50 Bd VFT channel is calculated as follows =10 log (2100 Hz/80 Hz) = -14 d. B Meaning , Noise power in 50 Bd/80 Hz data channel is 14 d. B below the noise power in 2100 Hz speech channel. In the AF mixer of the transmitter, the input signal levels for test tone, pilot tone, speech and telemetry are kept proportionate to their noise band width to maintain same SNR at the receiver. This is discussed under channel loading in next slide. “PLCC system” presented by P R Mekap (Tel) SLDC 35

Channel Loading PUNCOM PLCC The scheme for allocating the weights to voice and data channels is based on the noise bandwidth of each channel Speech(300 -2400 Hz) 2100/ 80 = 5. 0 Pilot(3923 Hz) = 50 baud 80/ 80 = 1. 0 Signalling(3825 Hz) = 50 baud 80/ 80 = 1. 0 200 baud FSK channel 360/ 80 = 2. 12 300 baud FSK channel 480/ 80 = 2. 45 600 baud FSK channel 960/ 80 = 3. 55 1200 baud FSK channel Same as speech = 5. 0 Speech with 3 d. B safety margin= 2 x 5 = 7 “PLCC system” presented by P R Mekap (Tel) SLDC 36

Channel loading (ABB PLCC) AF signal Signal Level assigned Considering noise power ETL Test Tone 0. 3/0. 8/1 KHz -10 dbu (Normal speech level) ETL Pilot tone (3780 Hz) -16 d. Bu ( 6 d. B below TT) ( -24 d. Bu in ETI version) Speech (safety margin=2) Voltage Weightin g 1 0. 5 -7 d. Bu ( 3 d. B above TT) 1. 41 50 Bd data -24 d. Bu ( 14 d. B below TT) 0. 2 100 Bd data -21 d. Bu ( 3 d. B above 50 Bd) 0. 28 200 Bd data -18 d. Bu ( 3 d. B above 100 Bd) 0. 4 -13 d. Bu (6 d. B above 200 Bd) “PLCC system” presented by P R Mekap (Tel) SLDC 0. 71 600 Bd data 37

Signal Levels ( PUNCOM) Speech ( with 9 d. B safety margin = 23 d. B above reference) Peak Envelope Power 9 d. B 14 d. B additional 9 d. B as safety margin leads to difference in SNR level for speech vs data in link budget calculation. 14 d. B above reference 1 k. Hz Test tone 600 Bd data 300 Bd data 10. 5 d. B above reference 6 d. B above reference 50 Bd data 23 d. Bm MAX PUNCOM Pilot/signaling “PLCC system” presented by P R Mekap (Tel) SLDC Pilot (50 Bd) as reference Level 38

Signal weighting and absolute levels VF Signals Signal Levels (PUNCOM) Absolute Level at HF Output d. Bm 0 Weighting d. Bm Absolute Level at input of Channel Modem d. Bm Speech(300 -3400 Hz) 0 5 +37 -16 Speech with 3 d. B safety margin +3 7 +40 -13 Pilot(3923 Hz) -14 1 +23 -30 Signalling(3825 Hz) -14 1 +23 -30 200 baud Channel -8 2 +29 -24 300 baud Channel -6 2. 45 +31 -22 600 baud Channel -3 3. 55 +34 -19 1200 baud Channel 0 5 +37 -16 “PLCC system” presented by P R Mekap (Tel) SLDC 39

PLCC Link Budget It is a mathematical model representing the performance of the proposed PLCC link for the given transmit power and carrier frequency. Propagation parameters like line attenuation, modal conversion loss, coupling loss, corona noise and many other factors affecting signal quality are being considered in calculating link budget. Finally we arrive at the SNR value for the voice and data channels. SNR is expected to be higher than 45 d. B. A link is not at all feasible if SNR is less than 15 d. B. “PLCC system” presented by P R Mekap (Tel) SLDC 40

Sample Link Budget : Boinda–Angul Puncom PLCC “PLCC system” presented by P R Mekap (Tel) SLDC 41

Modal Conversion Loss - A c (d. B) Additional Loss - A add (d. B) Corona Noise for Speech - P cor (d. Bm) Corona Noise for Data - Pcor (d. Bm) Channel # 1 1 6 -33. 7161107 = -15 + 10*LOG(1700/4000) -40. 9691001 = -30 + 10*LOG(320/4000) Coupling Loss - A coupl (d. B) Attenuation Constant - Alpha 1 Line Attenuation - A line (d. B) 6 0. 089075947 11. 56303787 = 0. 71{SQRT(364/1)/21}+364/1000 = alpha 1*40 km +2*1+6 Signal level of reference channel Pr (d. Bm) 19. 14912096 PEP – power[speech+data+pilot+signal ] Power 1 allocation for speech Psp (d. Bm) 42. 14912096 23 d. B above reference (d. Bm) 25. 14912096 6 d. B above reference Power allocation for data P data SNR (speech) in d. B 58. 30 SNR (data) in d. B 48. 56 Difference in two SNR level, because of 9 d. B safety margin in speech SNR>45 d. B “PLCC system” presented by P R Mekap (Tel) SLDC 42

SNR Calculation 1 - Corona Noise for speech (300 -2000 Hz) = -15 + 10 log (1700/4000) = -33. 7 d. B 2 - Corona Noise for 300 Bd data (320 Hz) = -30 + 10 log (320/4000) = - 40. 969 d. B 3 – Attenuation Constant (364 k. Hz; 21 mm) = 0. 71 { (364/1)/21} +364/1000 = 0. 089 d. B 4 – Line attenuation (40 k. M) = (40 x 0. 089 d. B) + 2 x 1 + 6 = 11. 563 d. B 5 - Signal level of reference channel Pr (50 Bd) = PEP – power[speech+data+pilot+signal] = 43 d. Bm – 10 log [ 6. 3095 (1700/80) + (320/80) + (80/80)] 2 = 19. 149 d. Bm 6 - Power allocation for speech Psp = 23 d. B above reference =19. 194+23 = 42. 149 d. Bm 7 - Power allocation for data Pdata = 6 d. B above reference =19. 194+6 = 25. 149 d. Bm 8 - SNR (speech) = (Psp– coupling loss– line attenuation) - corona noise for spech = 42. 149 - 6 - 11. 563 - (-33. 7) = 58 d. B 8 - SNR (data) = (Pdata– coupling loss– line attenuation) - corona noise for data = 25. 149 - 6 - 11. 563 - (-40. 969) = 49 d. B Remarks : 20 W PLCC operating at 320 KHz carrying speech plus data in Boinda - Angul 132 k. V line (40 km) gives acceptable SNR “PLCC system” presented by P R Mekap (Tel) SLDC 43

Part -III PLCC Equipments ABB ETL series “PLCC system” presented by P R Mekap (Tel) SLDC 44

PLCC Panel ( type: ABB ETL 41/42) Cabinet Modules “PLCC system” presented by P R Mekap (Tel) SLDC 45

ABB PLCC terminal ETL- 41 System data -- complies to IEC 495 Operating mode : Single side band Suppressed carrier Frequency range: 40 to 500 k. Hz (programmable in 4 k. Hz Steps) AF Bandwidth: 4 k. Hz (Speech band=300 – 3400 Hz) Transmitter RF output power : 40 W ( +46 d. Bm) Spurious suppression > 60 d. B Pilot channel : 3780 + 30 Hz Receiver RF sensitivity : - 24 d. Bm Receiver Selectivity : 70 d. B ( 300 Hz from band limit) Receiver Image rejection > 80 d. B Receiver IF rejection > 80 d. B “PLCC system” presented by P R Mekap (Tel) SLDC 46

Functional blocks of a ABB ETL 41 PLCC terminal AF Interfaces Basic equipment B 5 LA, B 4 LA P 4 LB=AF CONV Voice interface SA MO +12 V -12 V + 5 V Main Power Supply 1620 KHZ M O 0 -4 k. HZ E 5 LA P 1 LA PA P 4 LF P 4 LC Data interface Power Amplifier H P 4 LG P 3 LB d. B DE PILOT DE P 4 LC D E P 4 LD P 3 LB P 4 LB = AF CONV P 4 LC =IF CONV. P 4 LD= RX RF CONV MO=Modulator DE = Demodulator SA = Summing Amplifier PA= Power Amplifier H = “PLCC system” presented by P R RF-Hybrid Mekap (Tel) SLDC P 4 LF=TX RF CONV P 4 LG = CARR GEN P 1 LA = POW AMP P 3 LB = RF HYB 47

B 4 LA DC-converter G 4 AA DSP-Module G 4 AC Interface P 7 LB Channel shelf 9 R 4 R 6 R NSD 50 O 4 LATelcontrol interf. 7 R 6 R 6 R User interface 4 R 4 R basic “PLCC system” presented by P R Mekap (Tel) SLDC P 4 LF Tx--RF-conv. P 4 LG Carrier synth. 8 R P 4 LD Rx-converter P 4 LC IF-converter P 4 LB AF-converter B 5 LA Power Supply 48 VDC P 4 LA Pilot+Supervn O 4 LC 4 -wire. PAXintrf. 6 R G 4 AE Modem NSK 5 P 7 LA Power shelf E 5 LA/B Tx-Filter P 3 LB RF-Hybrid Channel 1 10 R 8 R 6 R Power amplifier 40 W ETL 41 module layout speech + data + protection Power shelf 48

ABB_ETL 41: Modulation Scheme ( double conversion) AF Band IF range (low) IF range (high) PLCC BAND (40 – 500 k. Hz) 0 -4 Khz AF IF 1 Carrier =16 k. Hz IF 1=16 -20 k IF 2 Carr =640 k. Hz 3 modulators 2 stage IF IF 2=620 -624 K SSB-SC TX FC= 724 k. Hz ( Programmable) TX=100 -104 “PLCC system” presented by P R Mekap (Tel) SLDC 49

ABB_ETL 41: Demodulation Scheme (Triple conversion) AF Band IF range (low) IF range (high) PLCC BAND (40 – 500 k. Hz) RX=104 -108 KHz SSB-SC 4 demodulators 3 stage IF IF 3=620 -624 RX FC = 728 k. Hz (programmable) IF 2=140 -144 IF 3 Carr =480 k. Hz IF 1 Carrier =16 k. Hz IF 2 Carr =160 k. Hz AF=0 -4 Khz IF 1=16 -20 K “PLCC system” presented by P R Mekap (Tel) SLDC 50

Multiplexing speech, telemetry and tele protection Speech 3. 4 k. Hz Programmable speech bandwidth Speech 3. 2 k. Hz Speech 3. 0 k. Hz Speech 2. 8 k. Hz Speech 2. 6 k. Hz Speech 2. 4 k. Hz Speech 2. 2 k. Hz Speech 2. 0 k. Hz 0. 3 plus 3. 6 4. 0 k. Hz tele protection (4 trip commands) 0. 3 2. 0 plus Speed 50 Bd Data/Tele metering (FSK signal) 100 Bd 200 Bd 300 Bd Center frequency 120 Hz steps 600 Bd 1200 Bd 2400 Bd 0. 3 “PLCC system” presented by P R Mekap (Tel) SLDC 3. 6 4. 0 k. Hz 51

Data Communication over PLCC link FSK PRINCIPLE Frequency shift keying digital Input digital MODEM Output analog Bit 0 = f 1 analog PLCC Analog Output f 1, f 2 Bit 1 = f 2 Digital Input “PLCC system” presented by P R Mekap (Tel) SLDC 52

Super Imposed Data channel (SID) 2220 Hz 60 ( BW=120 Hz) 2760 Hz 480( BW=960 Hz) 600 Bd 50 Bd SPEECH O 2 KHZ 2160 fc 2280 fc 3240 PROGRAMMING steps WITH NSK 5 1. Baud rate 2. Frequency TX 3. TX level of Modem 4. Tx level of PLCC 5. Impedance Matching with PLCC “PLCC system” presented by P R Mekap (Tel) SLDC 53

Tele protection architecture Substation A Substation B HV-line Protectio n Relay Teleprotectio n Equipme nt Physic al Link Telecommunication System Teleprotectio n Equipme nt Protectio n Relay Teleprotection System Protection System “PLCC system” presented by P R Mekap (Tel) SLDC 54

NSD-50 Plug in protection coupler with ETL-41 PLCC Signals: "AL" Common alarm (red) This LED lights on all the units that the alarm concerns. "RDY" Ready (green) The "transceiver ready" signal (TRY) "TRP" Trip (green) The tripping signal has picked up. "GRD" Guard (green) Lights whenever the guard signal is being received. "SNR" Signal-to-noise ratio (red) Lights whenever the signal-to-noise ration is too low. "LEV"Level alarm (red) The signal strength of the guard signal is not within the permissible limits. "Tx. A". . . "Tx. D" (green) Lights whilst the corresponding signal is being transmitted. "Rx. A". . . "Rx. D" (green) Lights whilst the corresponding signal is being received. "Tx. A/B", "Tx. C/D" (7 segment display) The number of commands transmitted is displayed (00. . . 99). "Rx. A/B", "Rx. C/D" (7 segment display) The number of commands received is displayed (00. . . 99). “PLCC system” presented by P R Mekap (Tel) SLDC 55

Digital PLCC ABB ETL 500 üImmune to noise üHigh speed data üSecured teleprotection HMI “PLCC system” presented by P R Mekap (Tel) SLDC 56

ETL 500 Versions with AMX 500 Speech + Teleprotection Data NSK 4 k. Hz ETL 580 ETL 540 8 k. Hz Data AMX 22 … 28. 8 kbit/s Pilot 4 k. Hz Data AMX + Teleprotection 40 … 64 kbit/s Pilot ETL 580 2* 4 k. Hz ETL 540 2* 4 k. Hz ETL 505 2* 4 k. Hz Pilot 4 k. Hz Pilot ETL 580 ETL 540 ETL 505 Data Speech + AMX Teleprotection 10… 12. 8 kbit/s 8 k. Hz “PLCC system” presented by P R Mekap (Tel) SLDC 57

Digital PLCC – latest version ABB ETL-600 HMI “PLCC system” presented by P R Mekap (Tel) SLDC 58

Digital PLCC ETL 600 -Technical data “PLCC system” presented by P R Mekap (Tel) SLDC 59

Digital PLCC : ETL 600 (256 kbps data) “PLCC system” presented by P R Mekap (Tel) SLDC 60

Digital PLCC – ETL 600 (secured teleprotection) “PLCC system” presented by P R Mekap (Tel) SLDC 61

Part -IV PLCC Test & measurements “PLCC system” presented by P R Mekap (Tel) SLDC 62

Test Instruments for PLCC Selective Level Meter “PLCC system” presented by P R Mekap (Tel) SLDC 63

Test Instruments for PLCC Selective Level Generator “PLCC system” presented by P R Mekap (Tel) SLDC 64