Does surge protection for data center switches require multi-level circuitry?

Surge protection for data center switches must adhere to the principle of graded energy discharge and employ multi-stage circuitry, as single-stage protection cannot simultaneously handle high current carrying capacity and low residual voltage. A typical three-stage architecture consists of: a first-stage gas discharge tube, such as the Etymotic 2R600L-8X6 (5kA current capacity), dissipating 80% of common-mode energy; a second-stage series inductor or resistor for current limiting; and a third-stage TVS, such as the 15KP58CA (15000W peak pulse power), precisely clamping the voltage to <100V. Decoupling impedances must be used between stages to ensure priority conduction of the first stage. The recommended spacing between the GDT and TVS is >10mm or a 10μH inductor in series. Actual measurements show that two-stage protection provides 3 times the surge withstand capability and reduces residual voltage by 60% compared to single-stage TVS protection, meeting the stringent IEC61000-4-5 Level 4 environmental requirements.