It is capable of arresting Iimp currents as large as 50 kA. Unit substations of individual buildings then should be fitted with the SPC25, a combination of SPD Type 1 and 2, that features dual varistors for higher safety and offers 25 kA of arrestable impulse current.

If the protected device is located within 5 m from the secondary substation or control cabinet, the system must be further equipped with a SPD Type 3 unit, for example the PI-3k. It is a high-frequency filter with attenuation min. 30 dB in the frequency band 0.15‐30 MHz that also features protective devices – varistors produced for rated currents from 16 to 400 A.

Whenever controlling electronics is being protected, it is recommended that SPD Type 3 be fitted directly within the device. The category of auxiliary SPD, which are fitted as the end-line devices in the electrical system (sockets) includes ZS-1.1 with optical signalling of correct function of the surge protection and ZS-1.2 which has a miniature piezosiren. Other type modules are ZS-1L and ZS-1P which are fitted in wall boxes below the socket, in floor boxes or gutters.

HAKEL also offers protection for situations where the roof of the building bears photovoltaic panels. Our recommendation is the PIVM PV V-series that mounts before the inverter and its interior is fitted with disconnectors which are deployed in the event of failure (overheating) of the varistors and with mechanical stop, that is inserted between the disconnected electrodes to prepare ideal conditions to kill a DC arc. Surge protection for alternating current is necessary, the best choice is the PIVM-12,5 V-series.

HS50-50/3+0 is a lightning arrester type 1 according to EN 61643-11 and IEC 61643-11.

HS50-50, HS50-50 DS and HS55 are the lightning arresters type 1 according to EN 61643-11 and IEC 61643-11.

B20 is the encapsulated gas discharge tube Type 2 according to EN 61643-11 and IEC 61643-11.

B20M Vseries is the encapsulated gas discharge tube Type 2 according to EN 61643-11 and IEC 61643-11.