Presentation on transmission line and their classification including, underground cables. overhead line plus long, medium and short transmission lines

1. Present by
Mahfooz Alam 2164-2018
Syed Hamza Abbas 2354-2018

2. Classification Of Transmission Lines

3. Transmission Line
 A transmission line is used for electrical power from
generating substation to the various distribution
units.
 It transmits the wave of voltage and current from
one place to another.
 The transmission line is made up of a conductor
having a uniform cross section along the line, air
acts as an insulating or di electric medium between
the conductors.

4. Classification of the Transmission
line
1.Overhead transmission lines,
 Short transmission lines,
 Medium transition lines,
 Long transmission lines.
2. Under ground cables.

5. OverHead Power Line
 An overhead power line is a structure used in electric
power transmission and distribution to transmit
electrical energy along large distances.
 It consists of one or more conductors suspended by
towers or poles. Since most of the insulation is
provided by the air, overhead lines low cost method
to provide large amount of electric energy.

6. Short Transmission Lines
 Line voltage is less then 20 KV.
 Length of transmission line is up to about 80 Km.
 Capacitance effect are small or negligible.

7. Medium transmission Lines
 Line Voltage is greater than 20KV but less than
100KV.
 Length of lines is about 50Km to 150Km.
 Capacitance is significant.

8. Long Transmission Lines
 Line voltage is very high, greater than 100KV.
 Length of the overhead line is more than 150Km.

9. Advantages
 Cheaper to install and maintain as compared to
underground cables
 Quicker to fix whenever faults develops.
 They have large transmission capacity.

10. Disadvantages
 Affected by environmental conditions such as
Temperature, Wind, Rain, Etc.
 Also affected by Thunder and Lightening.
 Not Very safe in densely populated Area.

11. Underground Transmission Lines
 Underground cables is the replacement of overhead
cables providing electrical power.
 They are protected from high wind thunderstorms
or heavy snow or ice storms.
 Underground cables can increase the initial costs of
electric power transmission and distribution but may
decrease operational cost over the lifetime of the
cables.

12. Advantages;
 Low chances of developing faults.
 Low maintenance cost.
 Not influenced by environmental conditions.
 More durable than overhead lines.
 More safer than overhead lines.

13. Disadvantages;
 Very expensive. It cost four times the overhead lines.
 Repairing of the underground cables is not easy.
 Maintenance cost is also very high.