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From: Boris Mohar
Subject: Re: polyswitches in vacuum
X-Newsreader: Forte Agent 1.92/32.572
Date: Wed, 20 Nov 2002 12:28:08 -0500
NNTP-Posting-Date: Wed, 20 Nov 2002 12:29:24 EST
Organization: Bell Sympatico
On 20 Nov 2002 15:33:12 GMT, Mike Poulton wrote:
>On 20 Nov 2002, Mike Hubert said:
>> Since heat is allowed to build up the device will probably trip much
>> quicker... but does it do so in a predictable way? I'm just wondering
>> if there is some way of designing around this...
>You could mount it on a black heatsink. Radiative dissipation will be
>the only real mode of heat loss, and it takes a good bit of black
>surface area to radiate much. AFAIK, the only reliable method of
>determining the new characteristics of your polyswitch/heatsink combo in
>a vacuum would be to test it in a bell jar. Keep in mind that the
>circuit would only be protected when in a vacuum. The extra heat
>dissipation in open air would keep it from tripping under anything but
>the most extreme overloads.
Do not forget to account for the thermal mass of the heatsink
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