Surge protection: why Mersen reinvented the standard

(See Mersen at Machine Building North, 13 May 2026, on stand 125)

It is in this evolving environment that Mersen chose to rethink surge protection from the ground up. The result is the launch of its new K1 and K2 ranges - not just an update, but a redefining of how surge arresters should be designed, installed and understood.

The hidden complexity of surge protectors

For many users, a surge protection device still seems like a simple accessory added to ensure compliance or protect equipment. Yet the reality behind the scenes is far more intricate. According to the IEC/EN 6164311 standard, every surge arrester must work in tandem with an associated protective device. In practice, this often leads to the need for additional upstream protection - and this is where things get complicated.

Field feedback has repeatedly highlighted the same pain points. Protection values in amperes change from one model to another; interpretation of installation tables varies depending on the manufacturer; questions about selectivity with the main protection keep resurfacing; and, to make matters worse, the dedicated protection devices are often bulky and difficult to position in increasingly compact switchboards. What should be a straightforward operation becomes a technical labyrinth.

For many nonspecialist users, this complexity results in hesitation, installation errors or inconsistent standardisation.

Surge protection built on realworld needs

Mersen designed the K1 and K2 series directly from field experience. These new surge arresters integrate their own protection function directly within the product, up to 315 A. For most installations, this means installers no longer need to add special external protection - as long as the main incoming protection does not exceed that threshold.

But beyond this simplification, the product was engineered to deliver consistency and peace of mind: fewer components to manage, a more controlled installation process, and a drastically reduced risk of incorrect wiring or compatibility issues. Mechanical coding ensures cartridges cannot be inserted incorrectly, helping eliminate one of the most common mistakes observed in the field. At the same time, LCF technology provides enhanced durability, and improved resistance to temporary overvoltages gives the devices the robustness required by modern applications and new energy uses.

By removing the need for a backup fuse up to 315 A and by delivering a fully integrated protection ecosystem, the new K1 and K2 lines transform the user experience. Designers and installers face fewer technical decisions and fewer regulatory constraints. Panels become easier to standardise across multiple projects. And performance remains consistent, sustained and controlled, regardless of the application.

In situations where constraints exceed the standard case - like main protections above 315 A, very high shortcircuit currents, or specific protection strategies based on habit or safety logic- Mersen offers a tailored complement: the SSD range. These compact fuses are designed to protect surge arresters efficiently while minimising space, ensuring selectivity and fitting easily into existing architectures.

Rather than a onesizefitsall approach, Mersen delivers a coherent, adaptable ecosystem.

With the K1, K2 and SSD families, Mersen is not just launching new products; it is offering a new, clearer way to think about surge protection. This new generation of SPDs is the result of extensive field observation, listening to users and understanding their frustrations. From that groundwork emerged a solution that is intuitive, robust and deliberately conceived with the installer in mind.