ZOTUP IN PILLS | HOW TO CONTAIN THE LENGTH OF SPD CONNECTIONS?

One of the most important issues complicated for this reason which concerns the world of surge arresters is without any doubt the length of the connections: the sum of the length of the cables from the phase derivation to the arrester terminals up to the equipotential earth connectionmust not be greater than 50 cm >. 

This is because in high frequencyeach meter of cable is equivalent to an additional voltage drop of 1000 volts(1 micro Henry per meter) which adds to the Up protection level offered by the SPD. And’ I know, in fact, that the unloader's task is providethe highest level of protection effective as possible, which translates into the most efficient Up. low possible. Therefore, it would be a serious mistake to reduce its performance just because of poorly executed wiring. Unfortunately, there are situations in which being able to keep the length of the cables under half a meter is difficult. extremely difficult, just think of a small resin panel or a 2 m metal cabinet with line arrival from above and earth bar at the bottom.

In these cases, how can you proceed? 

To cancel the inductive drop of the cable, a V connection can be made, also called an in-and-out connection from the SPD, which is facilitated in many arresters by the presence of double terminals.&nbsp ;In this way the two equal and opposite electromagnetic fields cancel each other out, as illustrated onpage. 78 of our Applications Manual 3. (Download the complete Manual from our "SERVICES" section). 

Another viable solution is that of joining the ground bar placed at the bottom of the panel with a second ground bar placed vertically, bringing the equipotential connection closer to the arrester and thus considerably reducing the length of the connections. p>

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Pill suggested by Ing. G.A.P.