REFLECTOR: Circuit Breakers/Switches

[Laurence Coen]

Tom,

The Ztron box uses this type of technology if not in fact this particular device.  I use the PTC type resettable fuse.  A conventional fuse uses a low melting point metal element that melts on overload and interrupts the circuit.  This follows the KISS principal but having to replace it in flight doesn't.  Let's say your avionics stack goes dark.  This involves multiple devices only one of which developed a fault.  You turn them all off and replace the fuse.  Then turn them back on one at a time till the bad box again blows the fuse.  Now you leave that one off and again replace the the fuse assuming you had two spares.  A PTC works like a fuse but when you turn off the power it cools down and resets itself which makes life simpler.

Here's how they work.  They consist of two metal plates separated by a layer of polymer/carbon particles that is solid at low temperature.  In this state the carbon clumps together and is conductive.  On over current the polymer melts and the carbon particles separate switching the device to the high resistance state.  Switching off the avionics stack in effect replaces the fuse.  In honor of St. Valentines'  Day I call this the "KISS, KISS" principal. 

Larry Coen
N136LC


From: Tom Falls 
Sent: Friday, February 10, 2012 8:59 AM
To: Velocity Aircraft Owners and Builders list 
Subject: Re: REFLECTOR: Circuit Breakers/Switches


I found this white paper on electronic CB's. 
http://www.ti.com/lit/an/slua131/slua131.pdf 


Sounds like "magic bullet" technology to me, but then I'm not very well versed in this electronic stuff (over my head). Also don't know whether or not this is the technique used by Ztron.


Tom

On Feb 10, 2012, at 7:58 AM, Mark Magee <edjonesbrady at gmail.com> wrote:


  Brett,
  Can you give us the nutshell version of how these things function. I Googled 12V electronic circuit breaker last night and basically got nothing. Possibly my search terms were faulty.
  Despite my old Steam Gauge brain I am listening!

  Mark B. Magee
  N34XL XLFG

  Sent from IPhone 4

  On Feb 9, 2012, at 8:03 PM, "Brett Ferrell" <reflector at velocityxl.com> wrote:


    We have the Vertical power system, which is sort of electronic breakers, though a more complicated version.  Thus far we're pretty happy with it, but we only have a few handful of hours so it's early to say definitively.


    Brett



         -------Original Message-------
          From: Tom Falls 
          To: Velocity Aircraft Owners and Builders list 
          Subject: Re: REFLECTOR: Circuit Breakers/Switches
          Sent: 09 Feb '12 20:41

          I was hoping there was more experience with ztron and/or other solid state CB's. I like the size, price, weight and simplicity of this technology. I'm not inclined to jump on the ztron product until I know they can execute well. I'll hold off as long as I can before purchasing anything and keep researching and hoping ztron or someone else has a proven safe and reliable product.

          Tom

         




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