Below are the rules which we need to follow for the SPD mounting inside BlokSeT.
The surge arrester connections between the network (through the disconnection device) and the earth terminal block does not exceed 50 cm.
50cm rules of cable length is derived based on the inductance of the cable. So, the inductance of wire plays a major role to decide the cross section and length of cable.
The length of cable can be increased to 1 m if the load connected to switchboard are of category 3 or 4 as per below table.
4. BlokSeT frame of the cubicle or other metallic parts can also be considered as earthing point for SPD, because all the metallic parts in the cubicles has earth continuity.
Julkaistu:Schneider Electric Suomi