A SAMMINAR ON ELECTRICL TRANSMISSION LINE

CONTENTS 1. Introduction 2. Types of using transmission line 3. Classification of transmission line 4. Component of transmission line 5. Constants of transmission line 6. Effects on transmission line 7. Voltage regulation of transmission line 8.Transmission efficiency

1. INTRODUCTION General transmission line: a closed system in which power is transmitted from a source to a destination A two conductor wire system with the wires in close proximity, providing relative impedance, velocity and closed current return path to the source.

2. TYPES OF USING TRANSMISSION LINE 1. Supply types of transmission line are using 1.AC transmission line 2.DC transmission line 2. Construction type transmission line 1.Overhead head transmission line 2.Under ground transmission line

AC Transmission line 1.Single Phase AC system > single phase two wire system > single phase two system with mid point earthed >single phase three wire system 2. Three Phase AC system > three phase three wire system >three phase four wire system

DC Transmission line DC system 1.DC two wire system 2.DC two wire system with mid point earthed 3.DC three wire system

Construction type transmission line Over head transmission line Under ground transmission line

3. CLASSIFICATION OF TRANSMISSION LINE Transmission line are classified in three category 1. Short transmission line:- If the shunt capacitance of transmission line can be neglected for the purpose of performance analysis of transmission line and the length of the transmission line up to 80 km. and having low voltage range is 20kv to 30kv. 2. Medium transmission line:- the T.L. in which capacitance can be assumed to be only at one or two point and length greater then 80 km. and less then 200 km. and transmission having high voltage 100kv or 150 kv. 3. Long transmission line the T.L. in which capacitance is assumed to be distributed uniformly over the length of T.L. and the T.L. length greater then 200 km. and the voltage range is up to 150 kv.

4. COMPONENT OF TRANSMISSION LINE Supports Conductor Insulators Cross arm and clamps Fuses and isolating switches Phase plates Danger plate Miscellaneous Items

Supports Wooden poles Steel poles Rain forced cement concrete poles Lattice steel towers

Conductors 1. Commonly used conductor a.Copper b.Aluminium c.Steel cored aluminium d.Galvanised steel e.Cadmium copper 2.Stranded conductors

insulators 1.Pin type 2.Shackle type 3.Suspension type 4.Post type 5.Strain type 6.Stay type Cross arm and clamps

5. CONSTANT OF TRANSMISSION LINE Types of constant Resistant Capacitance Inductance Circuit Diagram of T.L. constant

6. EFFECT ON TRANSMISSION LINE 1.Corona effect:- it is the phenomena of ionization of air near the conductor surface in which hissing noise, violet glow, ozone production is observed near the conductor. Factor affecting of corona a.Atomsphere b.Size of conductor c.Spceing between conductors d.Line voltage 2. Skin effect:- it is the phenomena associated with current in conductors with portion of the conductor at the center is maximum magnetic flux linkage with associated due to which the effective resistance at the center of the conductors is as compare to the surface therefore AC current flow on the surface of the conductors this phenomena is known as skin effect.

Factors affecting of skin effect a.Types of conductor materials b.Frequency c.Diameter of conductor d.Shape of conductor 3.Proximity effect:- Inductance and current distribution in a conductor is also affected by presence of other conductor in its vicinity. This effect is known as proximity effect. Factors affecting of proximity effect a.Conductor size b.Frequency c.Reistivity d.Relative permeability of materials

7. VOLTAGE REGULATION OF TRANSMISSION LINE The percentage voltage regulation of the transmission line is defind as the ratio of potential difference between the sending end voltage and receiving end voltage by the voltage of receiving end voltage % voltage regulation = ((Vs – Vr)/Vr) *100 where Vs = magnitude of sending end voltage Vr = magnitude of receiving end voltage

8. TRANSMISSION EFFICIENCY The transmission efficiency is the ratio of power delivered by transmission line to the load at receiving end to the power send from sending end voltage. % ɳ = (power delivered to load) /(power delivered to load + losses)*100