Long Flashover Arresters
Long Flashover Arresters
1
What I’ll be presenting…
Introduction to lightning and lightning arresters What are Long Flashover Arresters? Why do we need them? How do they work? What are their types?
2
What is a lightning stroke?
It is an electric discharge between
◦ Cloud and earth ◦ Cloud and cloud ◦ Charge centers of the same cloud
3
Lightning stroke waveform
4
Types of lightning strokes
Direct Stroke Indirect Stroke
5
What does lightning do?
Strikes live power line jumps across insulator to reach grounded tower. Lightning channel across insulator acts as conductor causing a short circuit. Man-made power from live wire flowing through section of old lightning channel in an intensely bright arc.
6
Lightning arresters
A device used on power systems above 1000 V to protect other equipment from lightning and switching surges Under normal operation the lightning arrester is off the line On the occurrence of over voltage air insulation across gap breaks down and arc is formed providing a low resistance path for the surge to the ground
7
Metal Oxide Lightning Arrester
The metal oxide varistor (MOV) contains a material, typically granular zinc oxide, that conducts current (shorts) when presented with a voltage above its rated voltage They exhibit an extremely high resistance during normal operation and a very low resistance during overvoltages
8
What are LFAs?
A new simple, effective and inexpensive system for lightning protection of overhead distribution lines
Pole Top Arresters LFAs
Costly; Easily Destroyed Cheaper; Cannot be Destroyed
9
Need for LFAs
Prevent Damage to Power Lines by Lightning Strike
Enhance the Reliability Performance of power lines
Reduce Maintenance Costs of Power lines
10
How do LFAs Work?
Basic Principle
E
E Probability of Flashover
α Vnom α 1/L αE
1
What I’ll be presenting…
Introduction to lightning and lightning arresters What are Long Flashover Arresters? Why do we need them? How do they work? What are their types?
2
What is a lightning stroke?
It is an electric discharge between
◦ Cloud and earth ◦ Cloud and cloud ◦ Charge centers of the same cloud
3
Lightning stroke waveform
4
Types of lightning strokes
Direct Stroke Indirect Stroke
5
What does lightning do?
Strikes live power line jumps across insulator to reach grounded tower. Lightning channel across insulator acts as conductor causing a short circuit. Man-made power from live wire flowing through section of old lightning channel in an intensely bright arc.
6
Lightning arresters
A device used on power systems above 1000 V to protect other equipment from lightning and switching surges Under normal operation the lightning arrester is off the line On the occurrence of over voltage air insulation across gap breaks down and arc is formed providing a low resistance path for the surge to the ground
7
Metal Oxide Lightning Arrester
The metal oxide varistor (MOV) contains a material, typically granular zinc oxide, that conducts current (shorts) when presented with a voltage above its rated voltage They exhibit an extremely high resistance during normal operation and a very low resistance during overvoltages
8
What are LFAs?
A new simple, effective and inexpensive system for lightning protection of overhead distribution lines
Pole Top Arresters LFAs
Costly; Easily Destroyed Cheaper; Cannot be Destroyed
9
Need for LFAs
Prevent Damage to Power Lines by Lightning Strike
Enhance the Reliability Performance of power lines
Reduce Maintenance Costs of Power lines
10
How do LFAs Work?
Basic Principle
E
E Probability of Flashover
α Vnom α 1/L αE
References: Podporkin G.V, Pilshikov V.E, Sivaev A.D; “LIGHTNING PROTECTION OF MEDIUM VOLTAGE OVERHEAD LINES BY MODULAR LONG-FLASHOVER ARRESTERS”; IEEE Transaction on Power Delivery;Volume 18, Issue 3, Page(s): 781 – 787; July 2003 Orsino Oliveira Filho, Darcy Ramalho de Mello and Gloria Suzana Gomes de Oliveira; “TESTING OF LONG FLASHOVER ARRESTERS DESIGNED FOR DISTRIBUTION LINES”; Ninth International Symposium on Lightning Protection; Nov,2007 Podporkin, G.V. Sivaev, A.D; “LIGHTNING PROTECTION OF DISTRIBUTION LINES BY LONG FLASHOVER ARRESTERS”; IEEE Transactions on Power Delivery;Volume 3, Issue 3; pp: 814-823; July 1998 30