These devices prevent damages caused by transient overvoltages in industrial electrical equipment and installations. These damages can be disruptive, dissipative or destructive whatever their origin: power or equipment disturbances, switching on and off, lightning strikes, utility grid switching. The core of Surge Trap is a TPMOV Thermally Protected Metal Oxide Varistor. It leads to fail-safe surge protective devices needing no fuse for overcurrent protection. The devices are DIN-rail mountable. When using the pluggable model the user has only to replace the plug unit without removing the base. Pluggable is the premium offering in the Surge Trap line when Modular is an economic alternative. With UL and IEC models they can be used globally and for photovoltaic applications as well. A front visual indicator communicates the status of the TPMOV. Remote signalling is an option via an auxiliary microswitch.