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Re: Ground Fault Interupters and RFI filters



---------- Forwarded message ----------
Date: Mon, 29 Sep 1997 20:02:59 -0500
From: "Robert W. Stephens" <rwstephens-at-headwaters-dot-com>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Ground Fault Interupters and RFI filters 

> Date:          Sun, 28 Sep 1997 23:11:33 -0600 (MDT)
> To:            tesla-at-pupman-dot-com
> Subject:       Ground Fault Interupters and RFI filters 
> From:          Tesla List <tesla-at-pupman-dot-com>

> 
> 
> ---------- Forwarded message ----------
> Date: Sun, 28 Sep 1997 22:10:34 -0500 (CDT)
> From: Richard Wayne Wall <rwall-at-ix-dot-netcom-dot-com>
> To: tesla-at-poodle.pupman-dot-com
> Subject: Ground Fault Interupters and RFI filters 
> 
> 9/29/97
> 
> I recently added a 30 A circuit breaker/GFI to my power cabinet.  It's 
> placed before the main contactor and variac.  Following the variac 
> there is a 100 A RFI filter.  Without the main power transformer 
> connected, the GFI trips when power is applied.  It still trips when 
> either the neutral or hot is disconnected and the other remains 
> connected.  Removing the RFI filter stops the GFI tripping.  I replaced 
> the RFI filter with two 200 A EMI filters on both the neutral and hot 
> line.  Same thing happens as with the RFI filter.
> 
> Has anyone had this experience with GFIs and RFI filters?  Anyone know 
> what the mechanism is?
> 
> RWW
> 
Richard,

The GFI looks for and trips off whenever it senses a very slight 
leakage path of current from the hot side of the line to AC ground.  
Proper flow of current to the normal safe load should come back all on the 
neutral line.  Your RFI filters internally provide a leakage path 
from the hot terminal to ground by virtue of their internal 
circuitry.  This leakage is tripping the GFI.  The only way to get 
around this would be to ground your RFI filters to AC neutral and not 
earth ground.  That would negate much gained by use of the RFI 
filters.

I'm not convinced that GFI's will be any more useful on a Tesla 
coil than a screen door is on a submarine.  If I were you I'd 86 the 
GFI's.

rwstephens