Scribd
Upload
83 views12 pages

Presented To: Presented by

This document presents an overview of corona phenomenon in overhead transmission lines. It discusses critical disruptive voltage, factors affecting corona, and methods to reduce corona loss. Corona occurs due to ionization of air surrounding power conductors and results in a faint glow and noise. Critical disruptive voltage depends on parameters like air density, conductor irregularity, and diameter. Corona loss is the energy lost as light, heat, and chemical reactions. Reducing corona involves increasing conductor size, using bundled or hollow conductors, corona rings, and increased spacing between conductors. Corona can reduce transmission efficiency and cause interference issues.

Uploaded by

Eng Dlovan
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
83 views12 pages

Presented To: Presented by

This document presents an overview of corona phenomenon in overhead transmission lines. It discusses critical disruptive voltage, factors affecting corona, and methods to reduce corona loss. Corona occurs due to ionization of air surrounding power conductors and results in a faint glow and noise. Critical disruptive voltage depends on parameters like air density, conductor irregularity, and diameter. Corona loss is the energy lost as light, heat, and chemical reactions. Reducing corona involves increasing conductor size, using bundled or hollow conductors, corona rings, and increased spacing between conductors. Corona can reduce transmission efficiency and cause interference issues.

Uploaded by

Eng Dlovan
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
You are on page 1/ 12

Presented To : Presented By :

Dronacharya College of Engineering, Indubhushan Kumar


Corporate Office ,#76 P, Part-III, Sector-5, M.Tech , IIT Roorkee
Gurgaon (HR)-122001
OVERVIEW
 Corona Phenomenon

Critical Disruptive Voltage

Factors Affecting Corona

Method of Reducing Corona Loss

Disadvantage & Advantage of Corona


Corona in Overhead Transmission Line

Ionization of Air Surrounding the Power Conductors is called Corona

 Self sustained Electric Discharge Phenomenon

Dielectric Strength of Air equals to 30 kV/cm peak at NTP

Faint violet glow appears which is visible in the dark

Production of ozone gas & Hissing Noise


Figure : Corona Discharge
Critical Disruptive Voltage

Critical Disruptive Voltage


Vc = mo go δ r loge (d/r) kV/phase

where
δ = air density factor = 3.92b / (273 + t)
mo (irregularity factor ) = 1 for polished conductors
= 0·98 to 0·92 for dirty conductors
= 0·87 to 0·8 for stranded conductors

Visual Critical Voltage


minimum phase-neutral voltage at which corona glow appears all
along the line conductors.
Corona Loss
Formation of corona is always accompanied by energy loss
which is dissipated in the form of light, heat, sound and chemical action

 Power loss due to corona is given by :


 Atmospheric Factors

 Field Around the Conductor

 Conductor size

 Spacing between conductors

 No. of Conductor/Phases

 Profile of Conductor

 Surface Conditions of Conductor


 By increasing conductor size

 Using Bundled Conductors

 Using Hollow Conductors

 Using Corona rings

 By increasing conductor spacing


 Reduces the steepness of voltage Surge produced due to
Lighting or Switching

 Reduces the Electro-static stresses between the conductors


 Loss of Power

 Reduces the Transmission efficiency of the line

 Radios and Television Interference

 Inductive interference with neighbouring Communication


lines
[1] Leonard Loeb “Electrical Coronas ,Their Basic Physical Mechanisms”
University of California Press 1965

[2] Junhong Chen, "Direct-Current Corona Enhanced Chemical


Reactions", Ph.D. Thesis, University of Minnesota, USA. August 2002

[3] C L Wadhwha “Electrical Power Systems”, New Age International (P)


Limited Publishers 5th Edition

[4] https://electricalnotes.wordpress.com/2011/03/23/what-is-corona-effect/
(Assesed on 7th July 2017)
THANK YOU……

You might also like