"Bass, Jerry" wrote:

Yes, I install 5 PTC Chips for Switched output like Lights, Strobes and

etc.

Then put 8 PTCs for non-switched distribution.  The LED lights if the

PTC

opens. You have to remove the load to reset.

I tried them by short circuiting the output and the chip opens quickly.

I have 9 amp down to 1.5 amp chips.  Usually limited to 30 amps per

board.

Today's equipment draws very little power. The wing tip running lights

seem

to take the most.

Jerry Bass

I think I know what it is but tell me again Jerry. What is a PTC?
What does PTC stand for?

Paul Lamar

"Bass, Jerry" wrote:

Secret.
Positive Temperature Coefficient. As the temp goes up, the resistance gets
higher, unlike many things where the resistance goes down with temp.

Light

bulbs are another example.
Jerry Bass

So they dissipate more power when a short is applied?
Give us a little dissertation on this subject.

Paul Lamar

"Bass, Jerry" wrote:

Their called Resetable Fuses.  PTC's have a threshold or knee in its
temperature curve that causes them to go High resistance once a certain temp
(current) is reached.  I am sure the physical size of the chip has something
to do with as the lower current chips are indeed smaller.

In Normal operation, the PTC has many conductive paths and a very low
resistance. In an over current condition, the temperature of the polymer
rises. This reduces the conductive paths resulting in a dramatic rise in
resistance.

Jerry Bass

I think that covers it well. Thanks Jerry.

Paul Lamar
 
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