How far from a transformer can arresters be located yet still ensure an adequate margin of protection? As explained by Jonathan Woodworth in this edited contribution to INMR, the answer is seldom simple.

Surge Arrester is usually connected between the grid wire and the ground wire, but sometimes it is also connected near the electrical winding or between the wires. Surge Arrester is another important piece of equipment often used when communication cables are used to prevent lightning damage. Next,

There are some 200 to 300 million distribution transformers in service worldwide. Of that population, a few hundred thousand are likely protected in a fashion similar to what is shown below, taken from a single-phase distribution line in North Africa.

Distribution arresters have been used on power systems for over a century during which time there has been a complete changeover in housings from ceramic to polymeric. Porcelain arresters often had issues with sealing and water ingress that sometimes resulted in ‘clear sky, sunny day’ failures.

As surge protective devices, arresters mitigate the impact of events that might otherwise trigger outages.

A surge arrester is a device to protect electrical equipment from over-voltage transients caused by external (lightning) or internal (switching) events.