How to suppress lightning overvoltage in concentrators?

The concentrator may be susceptible to overvoltages from direct or induced lightning strikes, requiring multi-stage coordinated surge protection for suppression. The first stage (building-level) is achieved using an external surge protector (SPD). A varistor (MOV) such as 14D511K or a gas discharge tube (GDT) such as 2R600L-8×6 with a current capacity greater than 20kA (8/20μs) is installed at the concentrator's power input. The second stage uses a varistor (such as 7D390K) or a TVS diode (such as SMCJ33CA) at the board-level power input. The third stage uses a TVS diode for the chip power supply (such as SMBJ5.0CA). Each stage is isolated from the others by a common-mode inductor CMZ1211-501T or a decoupling inductor. Signal ports use a GDT+TVS combination. All protective devices must have short, thick grounding wires directly connected to the grounding busbar. The concentrator should withstand the combined wave test specified in IEC 61000-4-5 to ensure survival under lightning strikes.