Surge Protection Device

Over voltage is any voltage, whose peak value exceeds the appropriate peak value of the highest operating voltage in the LV power system. Over voltage is usually an accidental phenomenon, which differs in time history and the place of its occurrence. Its parameters are defined by its cause (lightning stroke, switching in heavy-current network and so on) and also by electrical character of the circuit (wave resistance, ending  impedance, discharge ability and  so on). In the past few years the range of current and voltage courses  for different uses has been standardized. These courses enable implementation of testing on equipment and constructive elements under the same conditions. In the  following  text  the most important parameters of  the most used standardized courses will be defined (according to EN 61 643-11, IEC 60-1 and CSN 34 5640).