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Z 16 OVP fuselink question

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wdaniell.longport(at)gmai
Guest

Posted: Thu May 03, 2018 6:25 am Post subject: Z 16 OVP fuselink question

The positive wire from the buss to master (and OVP module) to ALT relay is protected by 22AWG fuselink.



Can I use an ATC fuse instead?



I have reformed and simplified my electrical system based on AEC.Â  I now have a fuse buss instead of breakers etc.Â  I have a slot spare and to use an ATC fuse would be simpler.

Many thanks



Will





William Daniell



LONGPORT

+57 310 295 0744

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user9253

Joined: 28 Mar 2008
Posts: 1925
Location: Riley TWP Michigan

Posted: Thu May 03, 2018 10:34 am Post subject: Re: Z 16 OVP fuselink question

If you have the 5 amp alternator circuit breaker, then I think it would be OK to replace the fuselink with a 30 amp fuse (or 35 if it will fit).  A 22 awg fuselink can carry up to 40 amps before melting.  Keep in mind that if the fuse blows, the alternator will be disconnected.  It is not safe to replace a fuse while flying.

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_________________
Joe Gores

wdaniell.longport(at)gmai
Guest

Posted: Thu May 03, 2018 2:26 pm Post subject: Z 16 OVP fuselink question

Joe



ThanksÂ 

Let me refine my question...(forgive me if in being dumb)

"Is a 22awg fuselink electrically different from a 5amp ATC fuse or are they equivalent?"

Will

On Thu, May 3, 2018, 13:39 user9253 <fransew(at)gmail.com (fransew(at)gmail.com)> wrote:



 	  Quote: 	
		  --> AeroElectric-List message posted by: "user9253" <fransew(at)gmail.com (fransew(at)gmail.com)>

 

 If you have the 5 amp alternator circuit breaker, then I think it would be OK to replace the fuselink with a 30 amp fuse (or 35 if it will fit).Â  A 22 awg fuselink can carry up to 40 amps before melting.Â  Keep in mind that if the fuse blows, the alternator will be disconnected.Â  It is not safe to replace a fuse while flying.

 

 --------

 Joe Gores

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=479820#479820

 

 

 

 

 

 

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nuckolls.bob(at)aeroelect
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Posted: Thu May 03, 2018 5:24 pm Post subject: Z 16 OVP fuselink question

At 06:51 AM 5/3/2018, you wrote:

  	  Quote: 	
		  The positive wire from the buss to master (and OVP module) to ALT relay is protected by 22AWG fuselink.



 Can I use an ATC fuse instead?



 I have reformed and simplified my electrical system based on AEC.Â  I now have a fuse buss instead of breakers etc.Â  I have a slot spare and to use an ATC fuse would be simpler. 	


   A piece of 22AWG wire has a hard fault

   fusing characteristic on a par with a

   40-50 at MaxiFuse. You could use a

   MaxiFuse but it's bulkier than the

   fusible link.



 

 

   Bob . . .

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wdaniell.longport(at)gmai
Guest

Posted: Thu May 03, 2018 5:59 pm Post subject: Z 16 OVP fuselink question

Ok thanks appreciate the answer



22awg fuse link it is then.



Will



William Daniell

LONGPORT

+57 310 295 0744



On Thu, May 3, 2018, 20:28 Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:



 	  Quote: 	
		    At 06:51 AM 5/3/2018, you wrote:

  	  Quote: 	
		  The positive wire from the buss to master (and OVP module) to ALT relay is protected by 22AWG fuselink.



 Can I use an ATC fuse instead?



 I have reformed and simplified my electrical system based on AEC.Ã‚Â  I now have a fuse buss instead of breakers etc.Ã‚Â  I have a slot spare and to use an ATC fuse would be simpler. 	


 Â  A piece of 22AWG wire has a hard fault

 Â  fusing characteristic on a par with a

 Â  40-50 at MaxiFuse. You could use a

 Â  MaxiFuse but it's bulkier than the

 Â  fusible link.



 

 

 Â  Bob . . .

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wdaniell.longport(at)gmai
Guest

Posted: Fri May 04, 2018 9:02 am Post subject: Z 16 OVP fuselink question

Joe and Bob,

Thanks so much...as usual a real education.Â  Â I had no idea that a 22 AWG fuselink is equivalent to a 30-40AMP fuse.Â  Â Intuitively I thought it was much less.Â  Â Much appreciated.

So if a 22AWG wire is normally "rated" to 5A which means 10degC (Ch8- current rise presumably therefore needs 40A to get to melting point.Â 



By the same token the 16AWG fuselink at the starter contactor (from the alternator) and from the battery contactor to the buss performs in a similar way.Â  Â If this is correct the 16AWG fuselink rated at 12.5A for 10 degC current rise will melt at something like 100A.Â  Whereas the 12AWG wire it's protecting will melt at something like 150 .

Is this correct?Â  Â 



Will



William Daniell



LONGPORT

+57 310 295 0744



 

On Thu, May 3, 2018 at 8:24 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:

 	  Quote: 	
		    At 06:51 AM 5/3/2018, you wrote:

  	  Quote: 	
		  The positive wire from the buss to master (and OVP module) to ALT relay is protected by 22AWG fuselink.



 Can I use an ATC fuse instead?



 I have reformed and simplified my electrical system based on AEC.Ã‚Â  I now have a fuse buss instead of breakers etc.Ã‚Â  I have a slot spare and to use an ATC fuse would be simpler. 	


 Â  A piece of 22AWG wire has a hard fault

 Â  fusing characteristic on a par with a

 Â  40-50 at MaxiFuse. You could use a

 Â  MaxiFuse but it's bulkier than the

 Â  fusible link.



 

 

 Â  Bob . . .

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user9253

Joined: 28 Mar 2008
Posts: 1925
Location: Riley TWP Michigan

Posted: Fri May 04, 2018 1:08 pm Post subject: Re: Z 16 OVP fuselink question

See the website below for a pdf listing the fusing (melting) current of wires.  It is a lot higher than one might expect.  The choice of wire size has more to do with voltage drop and insulation properties than the ampacity of the wire.

http://www.hsmwire.com/New%20PDFs/Fusing_Currents_Melting_Temperature_Copper_Aluminum_Magnet_Wire.pdf

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_________________
Joe Gores

nuckolls.bob(at)aeroelect
Guest

Posted: Fri May 04, 2018 1:19 pm Post subject: Z 16 OVP fuselink question

At 12:01 PM 5/4/2018, you wrote:

  	  Quote: 	
		  Joe and Bob,



 Thanks so much...as usual a real education.Â  Â I had no idea that a 22 AWG fuselink is equivalent to a 30-40AMP fuse.Â  Â Intuitively I thought it was much less.Â  Â Much appreciated.



 So if a 22AWG wire is normally "rated" to 5A which means 10degC (Ch8- current rise presumably therefore needs 40A to get to melting point.Â 	


 Exactly . . . see https://goo.gl/zye61w 



   Circuit protection is about keeping insulation

   temperatures comfortably below maximum rated

   operating vales. Wire size is all about maintaining

   distribution voltage drops below acceptable levels

   based on system design goals. 5% is the max-drop

   rule of thumb although other values may be adopted

   by program managers.



   Wire sizing tends to be very conservative . . . unless

   you are as weight-sensitive as a moon mission or

   Voyager flight, the design rules will keep wires

   pretty cool.



  	  Quote: 	
		  By the same token the 16AWG fuselink at the starter contactor (from the alternator) and from the battery contactor to the buss performs in a similar way. If this is correct the 16AWG fuselink rated at 12.5A for 10 degC current rise will melt at something like 100A. Whereas the 12AWG wire it's protecting will melt at something like 150. 	


   Fusible links in vehicles are expected to protect

   major feeders of a distribution system against

   hard faults . . . generally experienced only during

   major disassembly of the vehicle. By hard fault,

   were talking many times hundreds to thousands of

   amps supplied by a battery . . . not the soft

   fault precipitated by a failing appliance.



 https://goo.gl/QEBeZs 



  	  Quote: 	
		  Is this correct? 	


   Generally . . . When we use plain-vanilla wire

   as a fusible link in the OBAM aircraft world, it's

   a good idea to use the silicone/fiberglas sleeving

   over it to limit the propagation of heat damage

   during a fusing event.  In the ground transportation

   industries, fusible links are fabricated from wire

   having friendlier outcomes during the fusing event.

   Hypalon insulation (A Dupont product that targeted

   electric locomotives in mines) is used on many

   fusible link replacement assemblies available at your

   local car parts stores . . . or in bulk wire on

   places like eBay.



 https://goo.gl/RH2eEY 



   The material selected for a fusible link has

   little to do the loads presented by downstream

   appliances. The wire in fusible link is EXPECTED

   to burn . . . at many degrees above the insulation

   rating. Selection of material is about reduction

   of risk in the rare but catastrophic event.



 



 

   Bob . . .

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