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fused or not

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bobnoffs

Joined: 04 Jul 2012
Posts: 132
Location: northern wi.

Posted: Sat Mar 26, 2016 4:26 pm Post subject: fused or not

i am mounting my capacitor about 3 inches from the main bus.i planned on connecting straight to the bus main lug with #12 wire and no fuse. should i fuse the cap. for 3'' run?



Â bob noffs

ceengland7(at)gmail.com
Guest

Posted: Sat Mar 26, 2016 6:36 pm Post subject: fused or not

On 3/26/2016 7:20 PM, bob noffs wrote:

 	  Quote: 	
		   i am mounting my capacitor about 3 inches from the main bus.i planned 

 on connecting straight to the bus main lug with #12 wire and no fuse. 

 should i fuse the cap. for 3'' run?

  bob noffs

Context?
	




If this is a filter capacitor for a dynamo alternator, shouldn't be a 

problem.

user9253

Joined: 28 Mar 2008
Posts: 1944
Location: Riley TWP Michigan

Posted: Sat Mar 26, 2016 6:59 pm Post subject: Re: fused or not

12awg seems way too big.

There is not much danger for a 3" wire shorting out.  But capacitors have been known to short, not likely but possible.

_________________
Joe Gores

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Mar 27, 2016 4:23 am Post subject: fused or not

At 07:20 PM 3/26/2016, you wrote:

  	  Quote: 	
		  i am mounting my capacitor about 3 inches from the main bus.i planned on connecting straight to the bus main lug with #12 wire and no fuse. should i fuse the cap. for 3'' run?

 Â bob noffs 	


   No . . . that wire is not at-risk for

   generating any smoke or burning of

   other wires. No would a fuse prevent

   the very rare condition where the capacitor

   goes bad, swells up, smells bad and sometimes

   bursts . . . the things should be on your

   periodic replacement list . . . say every

   5 years or so.



   Also consider experiments to see if the

   capacitor is necessary/useful. I've not been

   able to measure any operational utility beyond

   helping us get some PM alternator/rectifiers

   to self-excite.



 

 

   Bob . . .

bobnoffs

Joined: 04 Jul 2012
Posts: 132
Location: northern wi.

Posted: Sun Mar 27, 2016 4:35 am Post subject: fused or not

thanks guys for the info. i am told it is to keep noise out of the ecu.



Â bob noffs

On Sun, Mar 27, 2016 at 7:20 AM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:

 	  Quote: 	
		    At 07:20 PM 3/26/2016, you wrote:

  	  Quote: 	
		  i am mounting my capacitor about 3 inches from the main bus.i planned on connecting straight to the bus main lug with #12 wire and no fuse. should i fuse the cap. for 3'' run?

 Ã‚ bob noffs 	


 Â  No . . . that wire is not at-risk for

 Â  generating any smoke or burning of

 Â  other wires. No would a fuse prevent

 Â  the very rare condition where the capacitor

 Â  goes bad, swells up, smells bad and sometimes

 Â  bursts . . . the things should be on your

 Â  periodic replacement list . . . say every

 Â  5 years or so.



 Â  Also consider experiments to see if the

 Â  capacitor is necessary/useful. I've not been

 Â  able to measure any operational utility beyond

 Â  helping us get some PM alternator/rectifiers

 Â  to self-excite.



 

 

 Â  Bob . . .

bobnoffs

Joined: 04 Jul 2012
Posts: 132
Location: northern wi.

Posted: Sun Mar 27, 2016 4:40 am Post subject: fused or not

i guess i don't really know how much a cap. pulls initially. i am sure somewhere i saw a schematic using 12 ga. if this is overkill what is recommended for a 10000uf?



Â bob

On Sat, Mar 26, 2016 at 9:59 PM, 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)>

 

 12awg seems way too big.

 There is not much danger for a 3" wire shorting out.Â  But capacitors have been known to short, not likely but possible.

 

 --------

 Joe Gores

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=454201#454201

 

 

 

 

 

 

 

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user9253

Joined: 28 Mar 2008
Posts: 1944
Location: Riley TWP Michigan

Posted: Sun Mar 27, 2016 5:05 am Post subject: Re: fused or not

I do know what wire size to use for a 10000uf capacitor.  But a capacitor only draws lots of current when it is first energized.  And that is for such a short time (less than a second) that the wire does not even begin to warm up.  A wild guess would be to use 18 awg.  Maybe someone more knowledgeable will answer.

_________________
Joe Gores

yellowduckduo(at)gmail.co
Guest

Posted: Sun Mar 27, 2016 5:41 am Post subject: fused or not

FWIW I agree if there is no battery in the circuit.



If there is a battery then my advice would be to forget the capacitor.

I've run for many years without a capacitor with a 20 amp PM alternator 

and a small battery. I've run many different ecu based electronic 

devices (homemade and commercial) without a problem and without any 

evidence that a capacitor would add any value. Even running my ignition 

off that system makes no practical difference. Who needs extra parts and 

extra maintenance issues. Lots of urban legend involved with the use of 

this large capacitor from what I can tell. I'm not saying the battery 

replaces the capacitor, I'm just saying that I've no experience running 

without a battery.



Ken



On 27/03/2016 9:05 AM, user9253 wrote:

 	  Quote: 	
		   



 I do know what wire size to use for a 10000uf capacitor.  But a capacitor only draws lots of current when it is first energized.  And that is for such a short time (less than a second) that the wire does not even begin to warm up.  A wild guess would be to use 18 awg.  Maybe someone more knowledgeable will answer.



 --------

 Joe Gores





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=454211#454211

bobnoffs

Joined: 04 Jul 2012
Posts: 132
Location: northern wi.

Posted: Sun Mar 27, 2016 8:27 am Post subject: fused or not

well........one failure mode of an engine with elec pumps etc. is alternator power only. whether or not i ever need the cap. is another issue but it was recommended i use one. this is for the honda/viking 110 installation.



Â bob

On Sun, Mar 27, 2016 at 8:39 AM, C&K <yellowduckduo(at)gmail.com (yellowduckduo(at)gmail.com)> wrote:

 	  Quote: 	
		  --> AeroElectric-List message posted by: C&K <yellowduckduo(at)gmail.com (yellowduckduo(at)gmail.com)>

 

 FWIW I agree if there is no battery in the circuit.

 

 If there is a battery then my advice would be to forget the capacitor.

 I've run for many years without a capacitor with a 20 amp PM alternator and a small battery. I've run many different ecu based electronic devices (homemade and commercial) without a problem and without any evidence that a capacitor would add any value. Even running my ignition off that system makes no practical difference. Who needs extra parts and extra maintenance issues. Lots of urban legend involved with the use of this large capacitor from what I can tell. I'm not saying the battery replaces the capacitor, I'm just saying that I've no experience running without a battery.

 

 Ken

 

 On 27/03/2016 9:05 AM, user9253 wrote:

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

 

 I do know what wire size to use for a 10000uf capacitor.Â  But a capacitor only draws lots of current when it is first energized.Â  And that is for such a short time (less than a second) that the wire does not even begin to warm up.Â  A wild guess would be to use 18 awg.Â  Maybe someone more knowledgeable will answer.

 

 --------

 Joe Gores

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=454211#454211

 

 

 

 

 

 

 

 

 

 

 

 	
 

 

 ===========

 br> fts!)

 r> >  href="http://www.buildersbooks.com" rel="noreferrer" target="_blank">www.buildersbooks.com

 rel="noreferrer" target="_blank">http://www.matronics.com/contribution

 Â  Â  Â  Â  Â  -Matt Dralle, List Admin.

 ===========

  -

 Electric-List" rel="noreferrer" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List

 ===========

  FORUMS -

 eferrer" target="_blank">http://forums.matronics.com

 ===========

 b Site -

 Â  Â  Â  Â  Â  -Matt Dralle, List Admin.

 rel="noreferrer" target="_blank">http://www.matronics.com/contribution

 ===========

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Mar 27, 2016 9:59 am Post subject: fused or not

At 08:05 AM 3/27/2016, you wrote:

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



 I do know what wire size to use for a 10000uf capacitor.  But a capacitor only draws lots of current when it is first energized.  And that is for such a short time (less than a second) that the wire does not even begin to warm up.  A wild guess would be to use 18 awg.  Maybe someone more knowledgeable will answer. 	


   that short of run would be fine with 22AWG

   but most of the TC world uses 20AWG minimum

   under the cowl just for mechanical robustness.



   



 

   Bob . . .

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Mar 27, 2016 10:34 am Post subject: fused or not

At 07:33 AM 3/27/2016, you wrote:

  	  Quote: 	
		  thanks guys for the info. i am told it is to keep noise out of the ecu.

 Â bob noffs 	


   That IS the legacy rationale for adding such things

   and it's a deeply rooted idea did

   a failure analysis on a modern, 100A alternator

   that came equipped from the factory with a 680uF

   electrolytic capacitor mounted right to the back

   of the alternator.



         

 [img]cid:7.1.0.9.0.20160327122948.0099ede8(at)aeroelectric.com.0[/img] 



   I am quite certain that noise from this alternator on

   EMC laboratory equipment would not be materially

   reduced for having added the capacitor. I'd

   LOVE to see an EMC test report that illuminates

   the 'benefit'.

  

   I just purchased a spectrum analyzer that sweeps

   down to 1Hz and up to 2.4 Ghz. When I begin

   development testing on the next generation of

   PM alternator rectifier/regulators for B&C I will

   quantify the value of adding this component

   to our airplanes.



 



 

   Bob . . .

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