I need some means to increase the Hi-pot rating of an Ethernet port to 3000V to meet regulatory approval. The Ethernet controller module is housed in a large metal enclosure and an 18" patch cord connects the controller to a back panel RJ45 connector. The controller module uses a standard mag jack which has a hi-pot rating of 1500V. Redesigning the controller card is not an option at this point. I was planning on making a small PCB at the back panel with two RJ45 connectors and a LAN transformer in between. This would provide an additional 1500V to 4000V of isolation depending on the transformer chosen. Does anyone see any potential (no pun intended) problems with this approach? Is any biasing required and should the center taps be left floating?
Electronic – Ethernet – 3000V Isolation
ethernethipotisolation
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Best Answer
It may be interesting for you:
Isolation ratings are not added but the minimum is selected instead. For example, if your have 10 kV, 20 kV, and 30 kV rated insulation black boxes connected in series, the resulting insulation level will be min{10,20,30}=10kV instead of 10+20+30=60kV as you presumed.
Pulse Eng. # HX1224NL Ethernet transformer (for example again) has 4kVrms @ 50/60Hz A.C. rated insulation level. You need to clearly distinct between A.C. and D.C. insulation. Ethernet specifies the A.C. one.
To protect your scheme properly, you need to ground the center taps of the additional insulation transformer at the side connected to the equipment being protected. It is to eliminate the weak (1.5kVrms) insulation level of the controller module from the result.
P.S. All listed above is on so called basic insulation (provided during 60 secs typ after shock, used for safety) not other(s).