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Arda , 10-10-2024, 06:42 AM

Hello everyone,

In many designs, we see chassis acting as the Faraday cage for wire shielding, such as in Ethernet and USB cables. I understand that grounding approaches can vary depending on the application, but I have a specific question about whether and how to connect the chassis to ground.

Some applications suggest connecting the chassis to ground through the mounting holes, as screws and plating conduct to the enclosure. Others recommend adding a capacitor between the chassis and ground to avoid direct DC connection while maintaining AC grounding.

I’d like to hear your thoughts and experiences with this. Specifically, I’m interested in grounding practices in aviation and marine systems, where EMI/EMC considerations are critical. Do you have any references or best practices you could share regarding how these connections are handled in such sensitive environments?

Thanks in advance for your insights and any resources you can provide!

This way, your question clearly specifies the context (aviation and marine systems), making it easier for experts in those fields to provide relevant feedback.

QDrives , 10-10-2024, 08:06 PM

In most of the designs I did, the chassis was directly connected to Gnd. No EMC problems there.

However, marine world is special. Leakage current can cause havoc to ships due to elektrolyse. So chassis, Gnd and PE (Protected Earth) need to be known so that such leakage current cannot flow.
If you want to connect chassis to PE for safety and also have some none shielded cables going out, you connect the chassis to Gnd via capacitors.

For aviation I did not check the requirements for doing this. All I know is that shielded / non shielded cables have different requirement with regards to surge tests.
You would need to check the DO 254 standard for that. In my case the housing was plastic so nothing to connect to anyway.

Arda , 10-11-2024, 06:08 AM

Thank you very much for your answer. Appreciate it!