How does equipotential bonding in power FTUs suppress common mode?

Equipotential bonding reduces the potential difference between components and suppresses common-mode interference. A mesh equipotential bonding system is employed. All metal components (chassis, panel, rails) are interconnected via 6mm² copper wire with a connection resistance of less than 0.05Ω. The cable shielding is grounded at both ends and equipotentially connected to the chassis via shielded connectors. On the PCB, analog ground, digital ground, and power ground are individually connected to the equipotential reference point via 0Ω resistors. A CMZ3225A-501T common-mode inductor is installed at the power input, along with a CY-Y1-222K Y capacitor for common-mode filtering. Through equipotential bonding, the common-mode voltage within the system is less than 1V, and the common-mode rejection ratio is greater than 60dB, meeting the IEC 61000-4-6 conducted immunity 10V test requirements.