EMI Filter Leakage Current Issue in MRI System When Grounding Connected

Hi every body, i have a problem in EMI filter for MRI system. The cover of the EMI filter has a power when there is no grounding but when ground cable cable connected to the cover of EMI filter the neutral line gets a high leakage current. i had assumed the problem is poor grounding then improved the grounding system but still no change and the problem exists. please help me to fix this problem.

A typical EMI mains filter consists of capacitors from the live or live and neutral and neutral legs to ground, and inductances in series with the live and neutral wires.So if the ground (case) of the EMI filter is grounded, the capacitors from the live line will allow a (usually fairly small) current to flow to ground - this appears as a leakage current to ground and in extreme cases can cause earth leakage breakers to trip.  If the case is not grounded it will appear to have a voltage on it.Some filters have a fairly large capacitance from line to neutral but only small capacitances from line and neutral to earth, this minimises this effect.Here is an explanation with a sample circuit diagram.

Hi Abdo-To add to what David said, if you can disconnect the filter, check the capacitors with an ohmmeter.  Also inspect them closely to see if there is any evidence of heating. If the EMI flter also includes surge protection, like varistors or TVS diodes, one of those could have failed.When you mention that you get high leakage current when the ground is connected to the cover of the EMI filter- Is this the only ground on the system?  If it is, the leakage could be caused by something on the other side of the filter (further inside the MRI machine).-Rick

Any leackage in the cap  usually disc/ polyster cap of higher voltage rating   connected from smps  gnd. since smps gnd will be at a higher potentional than the orginal gnd. check cap in 10k range for any leackage afterdisconnecting one lead of the suspected capfrom the circuit.
Is your powe input cable 3pin or 2pin  if 2pin reverse the connection and check  the result.
Sambath