Core Gaps (fwd)

From:  Malcolm Watts [SMTP:MALCOLM-at-directorate.wnp.ac.nz]
Sent:  Wednesday, April 01, 1998 4:00 PM
To:  Tesla List
Subject:  Re: Core Gaps (fwd)

Hi Greg,

> Date: Tue, 31 Mar 1998 20:04:48 +0000
> From: "Gregory R. Hunter" <ghunter-at-mail.enterprise-dot-net>
> To: Tesla List <tesla-at-pupman-dot-com>
> Subject: Core Gaps
> Coiler Types,
> I've noticed that transformer cores with an air gap tend to have 
> current limiting properties, whereas transformers with continuous, 
> gapless cores have no ability to limit current.  (For example, cutting 
> a gap in a variac core to make a current limiter of it)  How does that 
> work?  Just curious.

Since most of the flux appears in the gap due to its comparatively 
high reluctance, that flux is poorly coupled to the winding unless 
most of the winding covers the gap which is not usually the case.