Newsgroups: alt.engineering.electrical,rec.audio.tech,sci.electronics.misc,sci.engr.electrical.compliance
Subject: Re: How HUMplug-e ground loop solver works ?
References:  <[email protected]> <[email protected]>
"Richard Crowley"  writes:

>  wrote ...
> > Could it simply be a ferrite-based toroidal choke placed in series in
> > the ground lead?  It would safely maintain the safety continuity, but
> > the high impedance would reduce the ground currents.
> 
> The ferrite choke would be "high impedance" only at high
> frequencies. It would do nothing for typical ground-
> loop currents.

With suitably selected big ferrite core and more than few turns 
it is very well possible to get millenries even at 50 Hz. 
For example 10 mH inductance at 50 Hz is around 3 ohms impedance. 
This value will definately reduce ground loop currents on 
normal situations, but would it be then too much to 
make the grounding connection not good enough for 
electrical safety. 

So my question is would any impedance value that is well 
effective for solving round loop problems too high to be 
added to the safety ground connection (would not be safe 
in rela life and/or woudl not meet safety regulations) ?


I have made ground loop solving products that have been 
connected audio and/or video lines. I have made many 
experiments on different constructions. For signal lines 
I have tried different ferrite material, toroidal cores 
(simular as used in toroidal mains transformers), 
E-cores etc.. Different contructions have their all good 
and bad properties. With suitable ferrite selection 
is possible to get inductances that are high enough 
for solving ground loop problems on signal lines.  
The downside is that materials with what I can get 
high inducances with reasonable number of turns  
tend to saturate quite easily. 



-- 
Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web links and documents at 
http://www.epanorama.net/