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A PRACTICAL TRAINING A PRACTICAL TRAINING SEMINAR ON PLCCSEMINAR ON PLCC

RAJASTHAN RAJYA VIDYUT PRASARAN NIGAM LTD.

INTRODUCTION TO PLCCINTRODUCTION TO PLCC Power Line Carrier Communication is the technology

which is used to communicate between electric substations through existing electrical cables.

It is mainly used for telecommunication, tele-monitoring and tele-protection between electric substations through power lines at high voltages. The data can be transfer at 9.6Kbits/sec over many miles of electrical cable.

BASIC PRINCIPLE OF BASIC PRINCIPLE OF PLCCPLCC

In PLCC the higher mechanical strength and insulation level of high voltage power lines result in increased reliability of communication and lower attenuation over long-distance.

Since telephone communication system can not be directly connected to the high voltage lines, suitably designed coupling devices have to be employed.

Coupling devices consists of high voltage capacitors in conjunction with suitable line matching units(LMU’s) for line impedance matching to that of the co-axial cable connecting the unit to the PLC transmit-receive equipment.

Carrier currents used for communication have to be prevented from entering the power equipment used in GSS as this would results in complete loss of power system.

PLCC Station. Line Matching Unit (LMU). CC. Earth switching. Lightning Arrestor. Wave Trap. Co axial Cable.

EQUIPMENTS USEDEQUIPMENTS USED

PLCC Station: It is the station where Transmitting, Receiving, amplification and Filtration are performed.

Frequency Range : 40 – 500 khz Audio Bandwidth : 4 Khz

Output Power : 10 – 80 W

PLCC PANEL TRANSMITTER/ PLCC PANEL TRANSMITTER/ RECEIVER RECEIVER

Line Matching Unit 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.

LMU functional

Coupling Coupling CapacitorsCapacitors

Coupling capacitor is connected between the line matching unit and the power lines to block the high voltage entering to PLCC equipment.

It couples high frequency carrier with power line.

Earth Switch: This is used for the maintainances of LMU. The main function of Earth switch is to ground the trapped charges.

Lightning Arrestor: This is used for arresting any A.C. high voltages spike entering to the LINE MATCHING UNIT.

Co- Axial cable: This is used for interconnection between PLCC Station and LMU for carrying high frequency signal.

       WAVE TRAPS or LINE TRAPS

•Wave traps – (WT’s) are used between the transmission line and the power stations to avoid carrier power dislocation in the power plant and cross talk with other power line carrier circuits connected to the same power station.

•WT’s also ensure proper operating conditions and signal levels at the PLCC transmit receive equipment irrespective of switching conditions of the power circuits and equipment in the station.

WAVE TRAP

TYPES OF TYPES OF COUPLING COUPLING

PHASE TO GROUND COUPLING:

PHASE TO PHASE COUPLINGPHASE TO PHASE COUPLING

Inter line couplingInter line coupling

CONCLUSIONCONCLUSION Project is based on communication over existing power line.

Main advantage:1. Modern infrastructure simplify the implementation.

2. Both communication & power transfer can be possible on same circuit.

3. Implementation cost is reduced.

ADVANTAGESADVANTAGES 1. 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.

2. 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.

3. Power lines usually provide the shortest route between the power stations. 4. 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.

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

6. 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.

DISADVANTAGESDISADVANTAGES 1. Proper care has to be taken to guard carrier equipment and persons

using them against high voltages and currents on the lines. 2. High voltage lines have transformer connections, attenuate carrier

currents. Sub-station equipments adversely affect the carrier currents. 3.  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, corona and switching processes.

4. The noise is also introduced in the signal due to bad weather conditions.

THANK YOU

QUERIESQUERIES