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From: "Klaus Vestergaard Kragelund"
References: <firstname.lastname@example.org> <3E271A4F.AE18B8AB@engineer.com>
Subject: Re: Strange behaviour - core saturation puzzle
Date: Sun, 19 Jan 2003 16:53:53 +0100
X-Newsreader: Microsoft Outlook Express 6.00.2800.1106
Organization: TDC Internet
"Chris M" wrote in message
> Hi Klaus...
> WHy is one side of the coil shorted?????
The coils are for a common-mode RFI filter. But due to imperfectations of
the coil some differential inductance (leakage) is precent. THerefore the
large differential current in the coil will eventually saturate the coil. So
to test the coil as it is used - one side is shorted.
> You really need to keep it open or use the entire winding...
> The type of test your running needs to have a DC current source in series
> with a AC voltage source...
> This way you can measure the inductance with the AC at DC current
> As for why the your sat level moves down with increasing
> frequency...this is because the BH loop is not constant for all
> frequencies.....the BH loop will have more headrrom at the lower
> frequency.....the flux density will be the same , of course, but the
> lower frequency loop will sat a bit later...
The frequence of the applied signal does not change - it is a DC source
applied to the winding for about 50us. However the frequency of repetition
of that pulse is what I'm changing - but that will not alter the applied DC
> Also the core will have a Volt-Second (time constant) to a step
> function..this will be a first quadrant pulse permeability loop....
This is not clear to me - could you elaborate on this?
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