SP7 series SPD suitable for TN-S, TN-C, TN-C-S, TT, IT power supply system with AC 400V and below, 50/60Hz, used as equipotential connection at the boundaries of LPZOA and LPZO1 zone or LPZOB and LPZ1 zone, make lightning strike or surge protection for the power grid. 

The protector also suitable to combine with voltage limiting SPD to form “3+1” combination, used for TT system. The protector is not suitable for the system which the expected short circuit current exceed the rated follow on current breaking value.