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Re: [TCML] NTS Thermistors - Was: Hairpin circuit tripping breaker....



Yep - just put one in series with the Variac input terminal.  But they WILL
get hot (I**2 R = 20x20x.015 = 6Watts or more), and you want them to (so
they acquire the minimum hot-resistance), so you probably want at least a
small segment of lead-length, to put some thermal resistance between the
disk and any heat-sinking input stud.  I don't know about combustible, but
you don't want anything melt-able too close.

Regards, Gary Lau
MA, USA

On Sat, Jan 3, 2015 at 9:44 AM, David Rieben <drieben@xxxxxxx> wrote:

> Hi Gary,
>
> Thanks for the info. I have a 2 pair of these on order now. ;^) Before
> they arrive, I was just wanting to make sure that I correctly understand
> the proper utilization (and installation) of this device. My assumption is
> that you simply place the thermistor in series with the input to the
> offending inrush current producer (variac)? Also, do they produce enough
> heat during operation to require accommodation for appropriate clearance
> from combustible materials during operation? I would assume that they would
> not. I'm assuming "Rcold  - 1 ohm, Rhot - .01 ohm" refers to the startup
> vs. the energized resistance? If there is only .01 ohms of resistance after
> the circuit is energized, this should produce negligible heating, being in
> series with multiple ohms of reactive resistance from the energized variac.
>
> Thanks for the help,
> David
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