Electrical networks are low-frequency and, as a result, propagation of the voltage wave is instantaneous relative to the frequency of the phenomenon: at any point of a conductor, the instantaneous voltage is the same.
The IEC 62305 standard parts 1 to 4 (NF EN 62305 parts 1 to 4) reorganizes and updates the standard publications IEC 61024 (series), IEC 61312 (series) and IEC 61663 (series) on lightning protection systems.
Overvoltage may occur in electrical installations for various reasons. It may be caused by:
1.The distribution network as a result of lightning or any work carried out.
2.Lightning strikes (nearby or on buildings and PV installations, or on lightning conductors).
3.Variations in the electrical field due to lightning.
Like all outdoor structures, PV installations are exposed to the risk of lightning which varies from region to region. Preventive and arrest systems and devices should be in place.
Connections of a SPD to the loads should be as short as possible in order to reduce the value of the voltage protection level (installed Up) on the terminals of the protected equipment.
The main point to selection of a Type 2 SPD is Maximum discharge current Imax
To Selection of a Type 1 SPD, according to the following two points:
1.Impulse current Iimp;
2.Autoextinguish follow current Ifi
