Protection of the supply network TN-S, 3ph, 230V, the LPZ 1/2 interface, Type 2

Protecting the supply network on the LPZ 1/2 interface, Type 2, can be facilitated by installing a surge suppressor in the subordinate switchboard, e.g. the PIIIM-275/3+1, which is a varistor surge suppressor for 3ph networks TN-S, with a maximum discharge current (8/20) 50 kA.

The PIIIM Vseries is a varistor surge suppressor of the Type 2 in accordance with the ČSN EN 61643-11 standard. It should be installed on the interface of the LPZ zones 1-2 (in accordance with the IEC 1312-1 and ČSN EN 62305 standards), where it provides equipotential bonding and elimination of switching surges, which occur in supply networks entering the building.The PIIIM Vseries surge suppressor is mainly used in all areas of industrial and in residential buildings. They are installed into the subordinate switchboards or the control panels.The M designation specifies a design version with a removable module.

Fig. 1. An example of connecting the surge suppressor PIIIM-275/3+1

Notes:

1. You can also use the suppressor 4 + 0, but due to a higher risk of transverse overvoltage (L-N) it is preferable to use the 3+1 protection.