Insertion Loss Requirement and Low Level PCI Testing of HEMP Power Line Filter

High Altitude Electromagnetic Pulse (HEMP) power line filters are used to suppress the conducted HEMP on the power lines of a facility. The insertion loss requirement, however, is not very clear in any of the public standards related to HEMP. MIL-STD-188-125 1/2 requires Pulsed Current Injection (PCI) verification testing for filters and specifies maximum limits for norms of the measured residual internal transient currents and shielding requirements of a facility. IEEE-STD-1560 specifies how to test a filter for RF characteristic test, mismatched impedance, attenuation measurements (100 kHz to 30 MHz), S-parameter measurement up to 30 MHz and aperture leak testing by electric fields (1 GHz to 10 GHz). However, the conducted HEMP contains its maximum frequency content up to 50 MHz, where most of the pulse energy is concentrated. This paper aims to investigate the upper frequency range of insertion loss specifications for HEMP power line filters to ensure their effectiveness across all possible conducted environments. Additionally, low-level (1 kA) PCI testing is explored as a pre-compliance measure for HEMP filter design and performance verification.