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Re: Ground Fault Interupters and RFI filters
---------- Forwarded message ----------
Date: Mon, 29 Sep 1997 15:44:54 GMT
From: Jim Fosse <jim.fosse-at-bjt-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: 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?
>
Richard,
The "fault" is leakage current through the RFI filters bypass
caps. These caps are from line to ground and neutral to ground. The
current flow through them at 60Hz is larger than the trip current of
the GFI. Even if you solve this problem, GFIs are notorious for
tripping from RFI. I expect that the first time your TC discharges
that they will trip.
jim