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RE: Ground Fault Interupters and RFI filters





---------- Forwarded message ----------
Date: Mon, 29 Sep 97 12:18:30 UT
From: William Noble <William_B_Noble-at-classic.msn-dot-com>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: RE: Ground Fault Interupters and RFI filters 

the gfi trips when the difference between the hot and neutral currents exceeds 
a few milliamps - typically 10 if I remember right.  I would guess that the 
RFI filters have capacitors to ground rather than neutral, and that the 
conduction through these is tripping the gfi.  To prove this, isolate the case 
of the filter from ground.  IF the GFI no longer trips, that was the cause.  I 
suppose isolating the filter's case and then coupling the case to ground with 
a few microfarad capacitor would solve the problem (if the test above works) 
without greatly impacting the efficiency of the filter.

----------
From: 	Tesla List
Sent: 	Sunday, September 28, 1997 10:11 PM
To: 	tesla-at-pupman-dot-com
Subject: 	Ground Fault Interupters and RFI filters 



---------- 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