RE: terry's nst filter:power res overheating?

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

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

Hi Dan,

Of course, there are 'power' resistors like those weenie 5W surface mount
types :-D  But I am talking "POWER RESISTORS" :-)))  The kind you can heat
your house with.  350C continuous with a 10XW 5sec overload rating.  They
are far larger than they really need to be since, as you state, if they
were not terribly over speced they would incinerate everything around them.
 Originally, I used smaller ones but people whined about how hot they got.
So I speced the big ones so they "only" get to a 150F ;-))  They should be
mounted off the board preferably screwed to standoffs.  Keep them away from
poly caps!

http://hot-streamer-dot-com/TeslaCoils/MyCoils/BigCoil/protection.jpg

http://hot-streamer-dot-com/TeslaCoils/Misc/NSTFilt.jpg

http://hot-streamer-dot-com/temp/270_series.pdf

BTW - I have seen these used to heat equipment racks.  They ran them to a
dull red 24/7/365.  The racks were 20 years old and the resistors were
original.  They used the resitors because they were far more reliable than
a typical "heater".

Cheers,

	Terry


At 09:49 AM 9/18/2002 -0400, you wrote:
>
>Actually, this is completely wrong.  Although "some" power resistors can
>heat to the point where they glow red, there are a large number of power
>resistors which CANNOT take these type of temperatures.
>
>Also, although a resistor may be able to take 350C, the components or
>enclosure around it may not.  For example, 350C will definitely damage a
>FR-4 board and unsolder nearby components.
>
>Dan
>
>
>
>Hi Larry,
>
>Power resistors are basically space heaters.  At full power they can run
>350C or slightly glowing hot!  I use much larger power resistors than
>needed to keep the temp fairly sane but they will still get hot for sure.
>The heating you see is perfectly normal.
>
>Cheers,
>
>	Terry
> 
>
>At 01:25 AM 9/18/2002 +0000, you wrote:
>>I wired the unit up tonight.  less interferrence than the choke filters i 
>>was using. coil output seems slightly better.  but the problem is the power
>
>>resistors are heating up a bit more than I would like.  I am using
>>2 12kv 30ma nsts.  my gap is way maxxed out at somewhere just under 1/2".  
>>I'm assuming that the gap being wider than it should is probably causing 
>>overheating. the power resistors after 10mins of testing were about 110-120
>
>>degrees F.  the safety gap fires occasionally. any ideas?
>>I could post a link to a picture of the board plus the wiring layout i 
>>chose.  none of the other components are showing any signs of heating.
>what 
>>is the limit of the heating of the power resistors? perhaps 150F ?
>>am i just overreacting?
>>
>>larry.
>>
>>
>