The SUNTREE SUP1-40 AC SPD 420V 4P 20-40KA is a Surge Protective Device (SPD) for three-phase AC electrical systems, designed to protect electrical and electronic equipment from damage caused by voltage surges such as lightning strikes or sudden voltage changes in the electrical system. This device is used for electrical systems with a voltage of 420V, has 4 poles (3 phases and neutral), and can handle surge currents of 20-40KA. It is suitable for installation in commercial, industrial electrical systems, and large-scale solar power systems.