Re: I guess I'll have to wind my own inductor, again

From: Chris Carlen (crcarle_at_BOGUS.sandia.gov)
Date: 11/30/04 

Date: Tue, 30 Nov 2004 07:32:36 -0800

The Phantom wrote:
> On Mon, 29 Nov 2004 14:19:13 -0800, Chris Carlen
> <crcarle@BOGUS.sandia.gov> wrote:
>
>
>>Greetings:
>>
>>What are the intended uses for these things:
>>
>>http://www.jwmiller.com/pdf2/2200.pdf
>>
>>I tried hooking a pair of 27uH (they are also rated at 16uH at 9.8A),
>>with a pair of 8.2uF caps as a differential LCR filter at 100kHz, to a
>>load of 2.55ohms as the output filter stage for an Apex SA-60 PWM
>>amplifer.
>>
>>Idling with zero volts out the coils get warm. But when I put 7Vrms at
>>4kHz into the 2.5ohms, they get almost smokin' and whine as well as the
>>output being substantially attenuated. Simulation indicates only about
>>5A peak through the things with these numbers, and the output amplitude
>>shouldn't experience much attenuation even up to 10kHz.
>>
>>If these things can't even tolerate 4kHz at half their rated current,
>>what are they good for? Why do companies like JW Miller market products
>>that are not specified completely? Perhaps the only thing they are
>>really good for is EMI chokes.
>>
>>I guess I'll be making a gapped core inductor on a good HF core like the
>>3C90 I bought a while back. Hope ETD29 is big enough so I don't have to
>>order more...
>>
>>
>>
>>Good day!
>
>
> How large is the 100kHz component of current? According to the
> spec, the wire diameter is .053 (probably 16 guage), but the skin
> depth at 100kHz is .01 inches.

Not that much, about 2.1A p-p to 2.6A p-p riding on the lower frequency
ripple current, at the conditions described. A little more on average
when idling, 2.6A p-p. If anything, this would warrant slightly hotter
cores when idling.

JW Magnetics has confirmed they are for EMI.

Thanks for the input.

Good day! 

-- 
_______________________________________________________________________
Christopher R. Carlen
Principal Laser/Optical Technologist
Sandia National Laboratories CA USA
crcarle@sandia.gov -- NOTE: Remove "BOGUS" from email address to reply.
Quantcast