[EMI] 1500mV When computer is running!!!

[Ali]

My heavy-duty EPCOS 2x4, 7 µF feed-through EMI filter setup uses an isolation transformer. Each EPCOS feed-through EMI filter is rated for up to 63 amps at 250V.

I need to use an isolation transformer because each filter leaks up to 350 mA of current. They filter EMI through their metal body to ground, and I'm also using nanocrystalline cores to filter ground-wire EMI. Both filters together leak around 700 mA of current to ground, while a normal household RCCB is rated at 30 mA, so my house RCCB trips instantly.

When I connect these feed-through EMI filters to the isolation transformer, the RCCB no longer trips. However, the correct way to install them is to mount them on a metal chassis inside the main electrical panel and connect the chassis to an ultra-low-impedance main ground.

Unfortunately, this installation method is not suitable for a TT earthing system, which is what we use in my country. These filters are better suited to TN-C-S and TN-S earthing systems.

When I install these feed-through EMI filters before the RCCB in my TT earthing system, the neutral-to-ground voltage rises to 37V, which can damage electrical equipment. That's why I need to use them with an isolation transformer.

These feed-through EMI filters can filter both common-mode and differential-mode EMI from 2 kHz up to the MHz range without breaking a sweat. However, they cannot filter ground-wire EMI, so I'm winding the ground wire through five nanocrystalline cores to filter ground-wire EMI.

I'm only using this setup for my monitor because an isolation transformer adds impedance, which is not suitable for a PC. A PC needs an ultra-low-impedance power supply, but my monitor only draws 40 watts, so it doesn't need ultra-low impedance.

This setup works much better for my monitor, while I'm using OnFilter only for my PC.