Transient overvoltages are events which occur in a few microseconds (micro = 1 / 1 000.000) or a few milliseconds (mill = 1 / 1000) and their size changes between 5…10 kV. More overvoltages in these sizes are equal to the 8-10 time endurance limits of electronic devices.
How Does the Protection System Work?In the low voltage system, overvoltage coffers, tied between ground with phases and neutral with ground, in case of a coming impact, as moving from open circuit position to conduction, they extinguish the overvoltage on themselves. In other words, protection coffers take the impact voltage that system was going to expose, on. For this, in the norms of DIN – IEC graded protection was provided. As each degree diminishes the impact voltage a degree in result makes it harmless for the system. For common protection B class, moderate grade C class and sensitive protection D class protection modules are used.