Steep-front short-duration voltage surge tests of power line filters and transient voltage suppressors

Steep-front short-duration voltage surge tests were conducted on commercially available power-line filters and two types of transient voltage suppressors to determine their effectiveness for protection against nuclear electromagnetic pulse (EMP) induced power-line transients. The tested power line filters were single-phase industrial-type units in the 120/208 V and 277/480 V class rated at 100 or 200 A. It was found that the tested power-line filters provide from 38 to 54 dB of attenuation for steep front surges (20 to 40 ns rise time and 150 to 400 ns fall time to half-value waves for 2 to 20 kV peak voltage), and transient voltage suppressors add an additional 2 to 8 dB of attenuation. It was also found that while the tested power line filters provide good protection against EMP induced surges, degradation of the filter characteristics may occur and delayed failures of filter components are possible. Transient voltage suppressors reduce the EMP induced surge by 40% and thus provide some protection for the filter