RE: Cooling MOFSETS and IGBT's.

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "sundog by way of Terry Fritz <twftesla-at-uswest-dot-net>" <sundog-at-timeship-dot-net>

Hi all,

 Nope, not using water directly on the components.  Rather using a copper
block as a heatsink, then pumping water through the block.  The water never
comes in contact with the components, let alone any HV.  I do agree about SS
coils should run cool, as you want only the resistance to exist for the time
it takes to switch fully on or off (the faster the better).  However, any SS
device generates heat while it conducts, and the cooler it is, the more
better.

 The physical size of the copper block and it's cooling capacity vs a plain
heatsink makes it worth the effort to me for cooling, plus the added
advantage of moving the heat elsewhere (in my situation of the CPU cooler,
out of the computer's case).  Unless there was a dire need to submerge the
component, where I would use oil, I'd rather just secure it to a block of
copper with water running through it.  If heatsink/forced air cooling is
adequate for your components, excellent!  If it's too hot for your liking,
or you can't run any more power because of heat, look into water-cooling
with waterblocks.  The tiny waterblock I have does tons better than a
heatsink 5x the size.

  Whole lot less mess than submerging it in oil, you can pump any coolant
you wish through the block (water generally works best), and if you make
sure there's no leaks, it's extremely tidy and compact.

 hope that clears up any misconceptions!
												Shad
-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Monday, March 19, 2001 1:25 PM
To: tesla-at-pupman-dot-com
Subject: Re: Cooling MOFSETS and IGBT's.


Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net>

Hi,

Water cooling can pull about 10X the heat out of something compared to
regular convective or forced air cooling.  Since each high voltage section
would be a step up of about 1000 volts, current leakage may be a problem.
The current is DC in this type of SSgap coil (during charging) and then
there is the AC (~150kHz) during firing.  So basically the two ends of the
cooling tubing would be about 20kV from each other.  Oil may be the best
medium for such a system since it is an insulator but can carry off heat
too.  It could be reasonably contained in a little recirc system.

However....  I would hope a SSgap would not require anything but modest air
heat sinks.  If I go pumping hundreds of watts into heating the water, that
energy is coming directly out of the streamers energy...  I think the trick
is to keep the power dissipated in a solid state gap as low as possible so
the streamer gets all the power.

Cheers,

	Terry


At 09:54 AM 3/19/2001 -0800, you wrote:
>
>
>Tesla list wrote:
>>
>> Original poster: "sundog by way of Terry Fritz <twftesla-at-uswest-dot-net>"
><sundog-at-timeship-dot-net>
>>
>>
>>  On a thought, I do *NOT* recommend trying to watercool electrodes.  It'd
>> take a pump insulated to 30kv or so.  The $20 home-depot-special will
most
>> assuredly arc over and fry (and put HV on the mains).  So don't try it.
>>
>> Thanks Marc for thinkin' of using this on IGBS's!
>>
>>    Comments, questions and snide remarks welcome!
>>
>             Shad
>
>Distilled water as the coolant would work quite nicely, and hold off the
30 kV.
>
>or, run entire water cooling rig "floated" at the HV.
>