We offer a wide range of surge protective devices with different circuit design and construction to cover the different application needs. The overview below provides a comparison of fundamental characteristics for the priciple selection related to the operating conditions and protection needs.

design and construction for spds


SPDs with spark gap: 

SPDs with spark gap and trigger technology are intended for primary protection applications where the prospective short circuit current of the power distribution system at the installation point of the SPDs is lower than or equal to Ifi and for installations where coordinated SPDs with very short response time are provided for secondary protection. A typical application is e.g. in a TT system at a medium plant size comprising a main distribution board feeding first and second level subdistribution boards.


Limiting SPDs:

The wide range of limiting SPDs with NFC No Follow Current® technology allows optimum protection in most applications, also in large installations, where SPDs often operate independent from each other, and where reliable protection and high performance are required.


Combined SPDs:

Combined SPDs make use of GDT and varistor elements, with voltage switching and with voltage limiting function. In our production range, these SPDs have been optimized for those applications where no really high discharge capability is required, as for example residential applications.


Combined SPDs with additional filter:

Combined SPDs with additional filter are used where high continuity of service is required like data centers, DCS (distributed control systems), etc.. These SPDs do not only protect against transients due to lightning, but also against high frequency conducted interferences. They are applied where Electromagnetic Compatibility (EMC) is an issue and requires improvement of the system immunity.


protection against lightning effects


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