RFI Filters on VFD's on an IT Earthing System


Thread Starter

James Thomas

When using VFD's on an IT Earthing System (floating network) should RFI filters be used or not ?

If a 45 ohm resistor was connected between the transformer star point and ground to restrict fault currents would the above answer still apply ?

Hakan Ozevin

You cannot use RFI filters in a floating network, because the high-frequency disturbances should be transferred to the ground. Otherwise RFI filer will not work. Answer to your second question: no, because in such a case you are doing nothing but amplifying the disturbances. An RFI filter is a low pass filter which is sending (=shorting) the high frequency signals to the ground.

If you are using VSD in an very sensible location, then you must have a "grounded room".
You can contact to www.tesch.de who are experts on this subject. You can contact to me if you need further assistance.

Good luck

Hakan Ozevin
Thread starter Similar threads Forum Replies Date
S Power Generation 1
D Power Generation 0
N Process Control 3
J Process Control 10
M Programmable Logic Controller - PLC 4