Surge Protection Devices (SPD)

According to IEC 61643 Standard, lightning protection in a structure is complemented by installing a secondary or internal protection system. In this system, a series of Protection Devices (called SPD) are used to protect internal networks and equipments against lightning impacts. The system is designed to completely damp temporary surge currents and voltages in three levels and it uses three types of SPDs accordingly. For instance, in a power supplying network in a building these levels can be classified into main entrance, secondary branches and end-user points.
The SPD operation is so that in the event of surges the protected network is connected to ground in a very short time (a few microseconds) and after the transient situation is passed it backs to normal operation condition.