The AOUE2+3 series are Category 3 surge protection devices designed to provide excellent protection against transient overvoltage and are installed downstream of Category 2 surge protection devices. The application area of AOUE2+3 is to protect sensitive electronic equipment, such as home automation, IT systems, etc., which are usually installed in or near the switchboard. The Y-connection of the functional element provides balanced protection of the L and N conductors with complete isolation via the spark gap connection PE, which has the same MOV of the working conductor.