How to attenuate peak interference on power FTU lines?

Line spike interference mainly originates from lightning strikes, switching operations, and sudden load changes, characterized by high amplitude and steep rise times. The solution employs a three-stage energy dissipation architecture. The first stage uses a 2R600L-8×6 gas discharge tube (600V/5kA) to dissipate amplified energy; the second stage uses a 14D511K varistor (510V/4kA) for voltage clamping; and the third stage uses an SMCJ58CA TVS diode (58V/1500W) for precise protection. Simultaneously, a PBZ2012E600Z0T ferrite bead (600Ω@100MHz) is connected in series on the signal lines to filter high-frequency components, and an ESD15VAPB protection IC pin is connected in parallel. A common-mode inductor CMZ3225A-501T (500μH) is added to the power supply section. This three-level protection scheme can withstand a 6kV/3kA surge of a 10/700μs lightning waveform, with the peak voltage attenuated to below 100V and the rise time extended to the microsecond level, meeting the IEC 61000-4-5 Level 4 surge test requirements.