Selection of the anti-EMP primary filtering devices in the power network and calculation study

The main technology measures of anti-EMP in the civil defense shelter department´s power network are limiting and filtering circuits. High voltage and low voltage zinc-oxide (ZnO) lightning arresters are commonly selected for limiters. Filtering includes primary filtering and precise filtering. In primary filtering devices, the low voltage non-power compensation condenser components are commonly changed into star connection and grounding. Before entering the high shielding area, special precise power filters, which are more expensive, are fitted. However, up to now, nobody has researched how to design and calculate the primary filtering devices in detail. We present methods for designing, selecting and calculating primary filtering devices, based on more than ten years´ design experience. A table is presented of capacitor groups and capacitor value changes required for the design.