Re: Ferrite rings

To: tesla-at-grendel.objinc-dot-com
Subject: Re: Ferrite rings
From: jim.fosse-at-bdt-dot-com (Jim Fosse)
Date: Thu, 07 Mar 1996 05:11:29 GMT
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tesla-at-grendel.objinc-dot-com On Wed, 6 Mar 1996 20:00:58 +0700, you wrote:

>>From i_hopley-at-wintermute.co.uk Wed Mar  6 14:14 MST 1996
>Hi jim
>
>>Question, were these from "IBM AT" power supplies? telecom power
>>supplies?
>>
>
>They were from a Motorola Codex 6745 statistical multiplexer 
>
I was curious if I could scrounge bad power supplies from work. Oh
well, we don't use stat muxs.
>
>>The high value cores were from the common mode filter inductors, the 2
>>windings are effectively in anti parallel, for the mains current but
>>in parallel for the RFI. They can therefor have a high permeability
>>because the don't have to handle a large current.
>>
>Sorry have i missed another point here? does the higher permeability
>mean, despite higher inductance values, that the current capability is less
>due to the core saturating.(a few years since i was at college)?
>
Yes, the current  rating is lower. It's been 20 years since I took my
basic  EE courses, I'm having to relearn the basics:) Ed Harris may be
able to give a better explanations.

	Hint, Ed, et all. Can you help an old EE learn a new trick?

Ferrites for power applications have "gaps" intentionally placed in
the magnetic path, somehow this reduces the flux and prevents
saturation. The gap is either a ground low spot between two core
halves or by loose packing in a toroid.

	jim