OVR type 1 and type 1+2 are designed to discharge high current surges without any destruction of the installation. This surge protective device is chararcterized by its capacity to withstand impulse current with 10/350 µs wave form which simulate direct impact coming from a natural lightning current. Type 1 and Type 1+2 SPDs are placed at the entrance point of the installation, in the main distribution board for a global protection of this installation.