Conducted immunity requirements for equipment operational during high voltage network switching operations

Primary plant in modern substations is controlled and protected by electron ic equipment. When breakers and disconnectors operate, very large electric and magnetic transients may be radiated from the plant as interference. Thi s radiated interference can be picked up by cables and wiring in the substa tion and converted to conducted interference. The results of measured data on conducted interference are reported and the characteristics of these res ults and their correlation to existing standards discussed. The test result s show that different discrete ranges of frequencies exist and have to be a ccommodated by substation equipment. Of these, two frequencies (10 kHz and 10 MHz) are not included in IEC 61000-4-12, and it is recommended that thes e frequencies should be included Furthermore, for an air-insulated substati on with air-blast circuit breakers, it is recommended that the test level b e increased to as high as 10 IN where auxiliary equipment is within 10 m of the switchgear.