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The Seminar Topic is based
Power Line Carrier Communication
Presented ByAishwary verma .
INTRODUCTION OF PLCC
GENERAL DISCRIPTION OF PLCC
BASIC PRINCIPLE OF PLCC
CONSTRUCTION OF PLCC
TYPES OF COUPLING
ADVANTAGES AND DISADVANTAGES OF
INTRODUCTION OF PLCC
POWER LINE CARRIER COMMUNICATION
Power line carrier communication has been found to
be the most economical and reliable method for
communication in a medium and over long distance
in a power system.
For sending speech or other signals from point to
point in an interconnected power grid many
communication methods can be used. Some of them
are as following:
. Public Telephone Network
. Direct Lines
. Radio Circuits
. Power Line Carrier Communication(PLCC)
GENERAL MODULATION PRINCIPLE
SINGLE SIDE BAND TRANSMISSION
CARRIER FREQUENCY IS SPACED ON A
I.F. FIXED AT 16-KHZ
FULL DUPLEX MODE IS USED
LOWER SIDE BAND IS USED
THROUGHOUT ALL COMMUNICATION
SPECIFICATIONS OF PLCC
1)GENERAL Carrier frequency range :- 40 to 512 KHz
Useful AF band
:- 300 to 3,700 Hz
-peak envelope power:- 25 W
-side band power
:- 15 W
BASIC PRINCIPLE OF PLCC
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 result in high attenuation of even complete loss of
communication signals when earthed at isolator.
To prevent loss of communication signals, wave traps or line
traps are employed. These consist of suitably designed choke
coils connected in series with the line, which offer higher
impedance to RF carrier currents.
Wave traps also usually have one or more suitably designed
capacitors connected in parallel with the choke coils so as to
resonate at carrier frequencies and thus offer even negligible
impedance to the flow of RF currents.
The RF is prevented from entering the stations bus(yard) and
the power frequency is blocked of coupling capacitor.
The basic arrangement of connecting the WT and coupling
capacitor in PLCC communication is shown in the figure
(a) PHASE TO GROUND COUPLING
(b) PHASE TO PHASE
(c) PHASE TO PHASE COUPLING
(d) INTERLINE OR INTER CIRCUIT
•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.
Used are high voltage, high stability
mica capacitors with low losses
For lower voltage class of tuning units
with impulse test voltage rating upto 40
KV polystyrene capacitors are used
For higher voltage class of tuning units
with impulse test voltage rating upto 150
KV, capacitors with mineral oil
impregnated paper dielectric are used
PLCC (Power Line Carrier Communication) works on rectified AC
or main power supply. When supply goes off, we use BATTERY
CHARGER for proper functioning of PLCC, which provides supply
to the PLCC equipment for uninterrupted working. It provides DC to
the panel by battery of 48V. In this type 24 batteries are connected in
series and individually per battery has approximately 2V capacity.
Battery charger mainly consists of 4 sections –
1. Float charger
2. Boost charger section
3. Control section
4. Alarm section
:415 V AC 3-PHASE
: +/- 20%
FLOAT CHARGER :
:20 TO 40 AMP
- 43.2 to 67.2 V
- 25-70 Amps.
PLCC Unit Provide Five type of
2:COMPRESSOR & EXPANDER
5:SUPERVISION & ALARMS
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.
1. Proper care has to be taken to guard carrier equipment and
persons using them against high voltages and currents on the lines.
2. Reflections are produced on lines connected to high voltage lines.
This increases attenuation and creates problem.
3. High voltage lines have transformer connections, attenuate
carrier currents. Sub-station equipments adversely affect the
4. 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.
It is obvious that an effective power lines carrier system must
overcome these difficulties.
Power line carrier communication has
been found to be the most economical
and reliable method for communication
in a medium and over long distance in a