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Polyfuses and Lightspeed Ignition

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msausen

Joined: 25 Oct 2007
Posts: 559
Location: Appleton, WI USA

Posted: Fri Mar 13, 2009 9:56 am Post subject: Polyfuses and Lightspeed Ignition

Nothing is wrong with traditional circuit protection and I would recommend it normally.  The current use case thread for Polyfuses that I started is  to address a unique situation that traditional wire protection cannot address without some additional risks.  Read through the recent threads and you will see what I mean.  I also changed the subject line to accurately reflect the thread going forward.



  As far as them resetting only when the total load is removed, I've heard conflicting stories on that and I'm sure Bob can set that straight once he starts looking more closely at them.  For me I'll have a switch that will remove that load so it's a moot point and I generally only do one wire per application.



Michael



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nuckolls.bob(at)aeroelect
Guest

Posted: Fri Mar 13, 2009 10:45 am Post subject: Polyfuses and Lightspeed Ignition

At 12:52 PM 3/13/2009, you wrote:

 	  Quote: 	
		  

Sausen)" <rvbuilder(at)sausen.net>



   Nothing is wrong with traditional circuit protection and I would 

 recommend it normally.  The current use case thread for Polyfuses 

 that I started is  to address a unique situation that traditional 

 wire protection cannot address without some additional risks.  Read 

 through the recent threads and you will see what I mean.  I also 

 changed the subject line to accurately reflect the thread going forward.



   As far as them resetting only when the total load is removed, 

 I've heard conflicting stories on that and I'm sure Bob can set 

 that straight once he starts looking more closely at them.  For me 

 I'll have a switch that will remove that load so it's a moot point 

 and I generally only do one wire per application.


	


   I believe we're thinking along the same lines.

   Here's a first pass at a always hot bus feeder

   protection module.



http://www.aeroelectric.com/Catalog/AEC/9033/AEC9033-700-1A_Feeder_Protection_(PRELIM).pdf



   Design goals:



   Accommodate the unique demands driven by polyfuse packaging

   (ECB mount).



   No latent failures that are not pre-flight detectable.



   Minimum parts count, assembly labor, bill of materials costs.



   Demonstrably acceptable performance over -40 to +70C

   temperature range.



   I've ordered a set of polyfuses that appear correct for

   this task. I'll brass-board the circuit and get some

   bench tests to look at reaction times and particularly,

   variability over range of operating temperatures (haven't

   played with the test chamber in months!).



   Given that a stock, prefabricated enclosure exists then

   the only unique fabrication item is an etched circuit

   board . . . and that's not a big deal. Except for the

   polyfuses (which ARE inexpensive) there are no components

   that are not already purchased in volume for other activities.



   Bob . . .

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mprather(at)spro.net
Guest

Posted: Fri Mar 13, 2009 11:44 am Post subject: Polyfuses and Lightspeed Ignition

Parens "(" in a file name (url, link) can be problematic...



http://www.aeroelectric.com/Catalog/AEC/9033AEC9033-700-1A_Feeder_Protection_(PRELIM).pdf

Matt-



 	  Quote: 	
		   

 <nuckolls.bob(at)aeroelectric.com>



 At 12:52 PM 3/13/2009, you wrote:

>

>Sausen)" <rvbuilder(at)sausen.net>

>

>   Nothing is wrong with traditional circuit protection and I would

> recommend it normally.  The current use case thread for Polyfuses

> that I started is  to address a unique situation that traditional

> wire protection cannot address without some additional risks.  Read

> through the recent threads and you will see what I mean.  I also

> changed the subject line to accurately reflect the thread going forward.

>

>   As far as them resetting only when the total load is removed,

> I've heard conflicting stories on that and I'm sure Bob can set

> that straight once he starts looking more closely at them.  For me

> I'll have a switch that will remove that load so it's a moot point

> and I generally only do one wire per application.



    I believe we're thinking along the same lines.

    Here's a first pass at a always hot bus feeder

    protection module.



 http://www.aeroelectric.com/Catalog/AEC/9033/AEC9033-700-1A_Feeder_Protection_(PRELIM).pdf



    Design goals:



    Accommodate the unique demands driven by polyfuse packaging

    (ECB mount).



    No latent failures that are not pre-flight detectable.



    Minimum parts count, assembly labor, bill of materials costs.



    Demonstrably acceptable performance over -40 to +70C

    temperature range.



    I've ordered a set of polyfuses that appear correct for

    this task. I'll brass-board the circuit and get some

    bench tests to look at reaction times and particularly,

    variability over range of operating temperatures (haven't

    played with the test chamber in months!).



    Given that a stock, prefabricated enclosure exists then

    the only unique fabrication item is an etched circuit

    board . . . and that's not a big deal. Except for the

    polyfuses (which ARE inexpensive) there are no components

    that are not already purchased in volume for other activities.



    Bob . . .

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