5. Surge arrester implementation and installation

5.1 Protective distance

In the event of lightning strikes or switching operations, due to the propagation phenomena inherent in transient overvoltages, two points on the same conductor may not be at the same potential. It is therefore illusory to imagine global protection of a network simply by installing a few lightning arresters, for example at certain network nodes.

• The protection offered by a lightning arrester is very local. So it's not enough to know the surge arrester's level of protection to know the surge voltage actually applied to the equipment to be protected.

  The lightning arrester's mains and earth connections have a linear inductance of around 1 μH/m, which must be taken into account when calculating...