4. Training overview
Name of industry : Rajasthan Rajya vidyut prasaran nigam limited
Location : 220KV BASNI GSS , Jaipur
Duration of training : 20 may to 11 july
Department of training : electrical engineering
5. About company
RRVPNL started working from july 1957
Sh.shailendra Agarwal,IAS is the chairman & MD of RRVPNL
RVPN provides the pathway for power within whole rajasthan
This is the body of big organization ACT, like public limited
companies
It works as electric power distribution regulation within the state.
6. Introduction
PLCC, Power Line Carrier Communication, is an approach to utilize
the existing power lines for the transmission of information.
This technology has been in wide use since 1950 and was mainly
used by the grid stations to transmit information at high speed.
Can use existing infrastructure for data traffic
Involves a lot of technicalities.
7. General modulation principle
Single side band transmission
Carrier frequency is spaced on a 4KHz
I.F. fixed at 16KHz
Full duplex mode is used
Lower side band is used throught all communication
8. Basic principle of PLCC
The communication system cannot be directly
connected to the high voltage lines suitably designed
coupling devices.
These usually consist of high voltage capacitor with
polaritical devices used in conjucation with suitable line
matching unit (LMU) for matching the impedence of line
to that of the coaxial cable connecting the unit of the
PLC transmit-receive equipment.
9. Specifications of PLCC
1) GENERAL:-
Carrier frequency range:-40 to 512KHz
Useful AF band:-300 to 3700Hz
2) TRANSMITTER:-
Peak envelope power:-25W
Side band power:-15W
10. Basic arrangement
The basic arrangement of connecting the WT and coupling
capacitor in PLCC communication is shown in figure
15. Wave 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
16. Tuning capacitor
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
Used are high voltage, high stability mica capacitors with low losses
17. Battery charger
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
18. Technical specifications
NORMAL INPUT :415 V AC 3-PHASE
INPUT VARIATION : +/- 20%
FLOAT CHARGER :
DC OUTPUT :50 V
OUTPUT CURRENT :20 TO 40 AMP
EFFICIENCY : >70%
19. BOOST CHARGER
DC output - 43.2 to 67.2 V
Output current - 25-70 Amps.
Efficiency - >80%
20. Maintanace & fault traction
Fault analysis:
in fault analysis the faulty devices are checked in this
serial or manner:
1. Telephone or tele operation signal
2. Cabling low frequency circuit or DC power supply
3. PLC equipment
4. HF transmission path
21. Maintainance and fault traction
procedure
The control circuit boards should be inserted far firmly.
The charger should be switch off once in every month.
The battery terminal should be connected first and AC input after
that.
All mounting bolts should be checked before energizing.
22. Applications
PLCC Unit Provide Five type of operation:
1:TELEPHONE FACILITES
2:COMPRESSOR & EXPANDER
3:EMERGENCY CALL
4:SIGNAL BOOSTING
5:SUPERVISION & ALARMS
23. Advantages
No separate wires are needed for communication purpose.
Both communication and power transfer can be possible on same
circuit
Power lines provides the shortest route between the power station
Increase reliability
Lower attenuation over long distance
Implementation cost is reduced
24. Disadvantages
Reflection are produced on spur lines connected to high voltage
line this increased attenuation and create other problem.
High voltage lines have transformer connections,which attenuate
carrier currents.
Noise introduced by power lines is far more than in case of
telephonic lines.
Proper care has to be taken to guard carrier equipment and
persons using them against high voltages and currents on the lines.
25. Key learning
PLCC is mainly used for telecommunication,tele-protection and
tele-monitoring,between electrical substation through power lines.
In a PLCC system the communication is established through the
power line.
The carrier frequency range is allocated to include the audio signal,
protection and the pilot frequency.
26. conclusion
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.