What is the impedance requirement between the edge box protective ground and the working ground?

The protective ground (PE) and working ground (GND) of the edge computing box should be highly isolated under DC and power frequency conditions, typically connected via a Y capacitor. Safety standard IEC62368-1 requires a contact current <0.25mA; therefore, a 1000pF 2kV capacitor with an impedance of approximately 3.2MΩ at 50Hz meets this requirement. However, in the high-frequency EMC band, low impedance is required to discharge common-mode current, with an ideal impedance <1Ω for 10-100MHz. This is achieved by connecting a 1MΩ RC network resistor and a 0.01μF electrostatic discharge capacitor in parallel between PE and GND, providing a high-frequency path. Furthermore, a large copper area with a spacing >2mm between the PE and GND areas on the PCB ensures withstand voltage. In the actual design, a 1000pF 2kV Y capacitor from Etymotic was selected, with enlarged pads and vias connecting to the main ground. The measured impedance curve at 100MHz is <0.5Ω, ensuring smooth discharge of ESD and EFT surges.