Din-Rail AC Din-Rail Surge Protector, primary protection with 10/350µs impulse caused by direct lightning currents. Type 1+2 SPD are heavy duty devices designed to be installed at the origin of the AC installation equipped with LPS, designed to protect 1, 2, 3 or 4 wires installed in 1 or 3 phase electrical distribution cabinets, customized to fit clients' needs, ease of installation & maintenance.