filter conducted emission
Hi !!!
You said your input are 3 phases 5 wires. It's a star configuration, with neutral and shielding.
First, you should try a LC star filter. I mean, a L on each phase, and a C between phase and neutral.
If your 3 phases are not exactly balanced, there should be a return current in the neutral wire, which is not filtered by the LC filters. If you can, you should use a triangle configuration...
There could be also a return current in the ground. Since you try to eliminate the conducted Emission, you should try to connect the shielding at only one end, the one of lowest impedance. If you fear common mode voltage, you could connect the other end with a impedance (R, or LC...)
This kind of problem is quite difficult to solve, it depend on the connections. You should try several configuration.... Good luck!!!
Hope it will help you !!!