Induced lightning overvoltage protection
Induced lightning overvoltages are very widespread phenomena and are believed to be the reason of 80% of outages that happen on distribution lines.
Overhead distribution power lines, as well as transmission line, represent extensive structure, which consists of phase conductors, line insulators and auxiliary devices. Normally their height does not exceed 10 m, which means that there are many taller objects in their proximity. If lighting strikes in the area surrounding a distribution line, most likely its target will be an object, for example a tree, building, telecom tower and other similar objects around the line. When lightning strike evolves, due to electromagnetic coupling between phase conductors and lightning channel, distributed charge along a certain section of the line appears on all phases simultaneously. As soon as lightning “touches” any object and circuit is closed, waves of overvoltages start traveling along the line.
Proceeding from certain discharge intensity and distance, the overvoltage peak occasionally reaches the level of 500 kV, which is supposed to be the maximum value. For engineering application it is considered that peak of an induced overvoltage is below 300 kV. To understand better, we will take an average 20 kV power distribution line and its 200 m section. If the lightning strike has an electric current of 50 kA, the excess of a line potential can be estimated as 200 kV.
In order to prevent the possible deleterious consequences of this phenomenon, such as conductor damages and outages, the overhead lines should be equipped with solutions ensuring Induced lightning overvoltage protection.
Induced lightning protection devices
The main function of line lightning protection devices meant for induced overvoltage protection (i-LLPD) lies in successful quenching of the follow current appearing on a line after insulators flashovers caused by induced overvoltages. Such devices also rule out the possibility of short-circuit faults. The protection of conductor/insulator and the prevention of power cutoffs does not require any specific ground lead or low values of footing resistance. i-LLPD should be installed on alternate phases in accordance with the principle «one pole ― one device».
Note, that all devices can be installed in combination with metal oxide arrester for providing highest degree of protection.
About Streamer products
Speaking about the harmful effect of interaction between lightning and power systems, the economic losses surpass the cost of lightning protection system to a great extent.
Streamer equipment ensures the ultimate reliability and security of your electrical supply network. The innovative technology and strict compliance with all the standard specifications and regulations form the truly great induced lightning guard.