Lightning Arrester
Lightning Protection System
The early streamer emission (ESE) concept During a storm, when the propagation field conditions are favourable, the OPR first generates an upward leader. This leader from the OPR tip propagates towards the downward leader from the cloud at an average speed of 1 m/µs. The triggering time ∆T (µs) is defined as the mean gain at the sparkover instant (continuous propagation of the upward leader) obtained with an ESE air terminal compared with a single rod air terminal exposed to the same conditions.
Conventional Lightning Arrester
Modern ESEAT Lightning Arrester
Working Principle
Lightning arrestor working principle is, once the voltage surge travels throughout the conductor then it reaches the location of the arrestor where it is installed. So it will break down the insulation of the lightning arrestor for a moment, so voltage surge can be discharged toward the ground. Once the voltage of the system falls under the fixed value, then the insulation will be restored among the ground & conductor. Further, the current flow toward the ground will be stopped.
Types of Lightning Arrester
Generally, lightning arresters are classified into different types. The construction of lightning arrestors is different based on its type but the working principle is the same. It provides a low resistance pathway to the surges in the direction of the ground. The types are
Horn Gap Arresters
As the name suggests, this arrestor has two metal rods in horn-shaped. The arrangement of these metal rods can be done around a small air gap. The distance between these two rods can be increased because they increase from the gap. The metal rods are located on ceramic insulators.
The connection of the horn can be done by connecting it to two dissimilar wires. One side of the horn can be connected to the line throughout a resistance & choke coil whereas the other side is grounded efficiently.
Multi-Gap Arresters
These types of arresters are designed with a sequence of metal cylinders that are insulated and divided through air gaps with each other. In the sequence of cylinders, the primary cylinder is connected toward the electrical line, whereas the remaining cylinders are connected to the ground by series resistance. Some of the gaps among the next cylinders contain a shunt resistance that grabs a surge when there is a surplus of voltage.
Valve-Type Arresters
These kinds of arresters are applicable to electrical systems that are high-powered. These devices include two main parts like a sequence of spark gaps as well as a series of non-linear resistor discs.
The working of these devices can be done whenever an extreme voltage causes the spark gaps to stroke & the non-linear resisters hold the voltage within the ground. Whenever the surge of surplus power stops, the spark gaps can be pushed separately by the resister
Pellet-Type Arresters
The designing of these arresters can be done with glass tubes that are filled with lead pellets. These are finished from an inside of lead peroxide coated through the lead oxide.
Lead oxide within the lead peroxide is not powerfully conductive. Once the lead oxide is heated up, it turns into lead peroxide and provides the place to flow the current. Whenever the flow of current is transmitted, then the lead peroxide will be changed reverse to lead oxide. This kind of arrester is not broadly used.
