X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from an-out-0708.google.com ([209.85.132.248] verified) by logan.com (CommuniGate Pro SMTP 5.2c1) with ESMTP id 2557194 for flyrotary@lancaironline.net; Wed, 05 Dec 2007 08:12:05 -0500 Received-SPF: pass receiver=logan.com; client-ip=209.85.132.248; envelope-from=msteitle@gmail.com Received: by an-out-0708.google.com with SMTP id b2so1016817ana for ; Wed, 05 Dec 2007 05:11:27 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:references; bh=qKHsm4ebO8jyYhkfIL992hqfToEXNtuSnYIzPgPou+4=; b=JDkykqGXRllGJZ9x9u0zB2FWLAZwEx+hZ8U0X2685PMg9S3gsIqeAoRZhNRoYToJp3qQe7Zoob64tYsHIEAn0njaQTtIIe6uTSZZklfXYn+V/9mI2vSKFYjx3u+rnsUrJcxhmfrvoZ1dFHZYpXLYDtDTZpZN047/ef9+byaAlxY= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:references; b=RoS/m2AfvBgkNAg5+1dmYhROtBcRC8u+z4Jb1eQBktrSM2ZuPeajfPzQBlMIKyejJLI7W94w4HPTPncrh37MgM4Rry05Gjz0IIiuYtwbr1G8PJmCo4NY/IzmKM3SLrDcaVlebRmA8GTSbBBXVvSmKZmAmBOKlHCPfFlQLaFQA0w= Received: by 10.150.191.10 with SMTP id o10mr736059ybf.1196860287564; Wed, 05 Dec 2007 05:11:27 -0800 (PST) Received: by 10.150.157.18 with HTTP; Wed, 5 Dec 2007 05:11:27 -0800 (PST) Message-ID: <5cf132c0712050511i3b319875t16e4fec3225d232d@mail.gmail.com> Date: Wed, 5 Dec 2007 07:11:27 -0600 From: "Mark Steitle" To: "Rotary motors in aircraft" Subject: Re: [FlyRotary] Re: circuit breakers In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_65_6688080.1196860287554" References: ------=_Part_65_6688080.1196860287554 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Al, Yes, wiring is done (airplane is flying). Although if there is a serious flaw in my design, I'm willing to modify things. I understand your philosophy of putting the essential bus next to the battery, but I followed Ed's argument and went with circuit breakers for all flight critical equipment. So, if I locate the circuit breakers next to the battery, I can't reach them to reset them in flight, which is the big benefit of using circuit breakers in the first place. The routing of the big feed wire to the essential bus is pretty safe from shorting on any ground sources, so I should probably remove the 60 amp fuse and hook it direct to the battery. Sounds like the best option. Mark S. On 12/4/07, Al Gietzen wrote: > > > > So, what's the most reliable method of getting the big fat wire from the > battery (in the tail) to the essential bus at the panel? I had initially > connected this wire directly to the battery (unfused), but later added th= e > big 60 amp fuse. Being a fiberglass plane, would a carefully run unfused > wire be preferrable to a fused wire? Is a relay more reliable than a big > fuse? Would a solid-state relay be even better? > > Fuses are very reliable, certainly more than a relay. I didn't put my > engine critical "bus" (actually a 6 place fuse holder) at the panel. I > preferred to put that 'bus' near the batteries, and then ran the smaller > wires (each now protected) to the switches on the panel, and on to the > engine. Things are then fault tolerant because blowing any one fuse doesn= 't > keep the engine from running. Also avoids a large noisy wire at the pane= l; > which can be more of an RF issue than the distributed smaller wires. > > > > Depending on where your large wire (10 or 12 AWG?) has to run, with no > risk of abrasion or shorting to other wires it can be fine unprotected. > Every case is different. > > > > I have a #2 wire running from the contactor near the battery in front to > the starter on the engine in the rear. No fuse or breaker is appropriate > for that. > > > > I assume you wiring is all in place, and not a work in progress. > > > > Al G > > > > Mark S. > > > > On 12/4/07, *Al Gietzen* wrote: > > > > That's what I did... Flight Critical bus is always hot, although I did ad= d > a 60 amp fuse back near the battery. > Mark S. > > Is that fuse in the only power path to the engine critical bus? I think > fuses are a very reliable way to go; but for this application they are > synonymous with "fault tolerance". IOW, blowing one fuse does not shut y= ou > down. Actually, I would also apply the fault tolerance idea to the use o= f > breakers for critical items. > > One of the nice things about our setup is we have dual plugs, dual > injectors, dual controllers, and dual fuel pump. That gives you the > potential for very high reliability - a failure of any one of the pair do= es > not put you on the ground. I chose to use a separate circuit to each to > gain failure tolerance. Each circuit is protected with a fuse, and the fu= se > holder is powered directly from both batteries with isolation diodes so e= ven > a battery failure doesn't stop the engine. > > Wires are cheap and light and very reliable. Fuses cost only pennies, so > change them out and check the contacts every annual, or every 6 months if > you feel like it. I like that better than a breaker that has been in the > panel for 10 years. Fault tolerance =3D high reliability. (I almost said = =96 > fuses and fault tolerance, but I don't want to start that fuses vs breake= rs > discussion again J ) > > FWIW, > > Al > > > > > ------=_Part_65_6688080.1196860287554 Content-Type: text/html; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline
Al,
Yes, wiring is done (airplane is flying).  Although if there is a= serious flaw in my design, I'm willing to modify things.  I under= stand your philosophy of putting the essential bus next to the battery, but= I followed Ed's argument and went with circuit breakers for all flight= critical equipment.  So, if I locate the circuit breakers next to the= battery, I can't reach them to reset them in flight, which is the big = benefit of using circuit breakers in the first place.  The routing of = the big feed wire to the essential bus is pretty safe from shorting on any = ground sources, so I should probably remove the 60 amp fuse and hook it dir= ect to the battery.  Sounds like the best option. =20
 
Mark S.

 
On 12/4/07, = Al Gietzen <ALVentures@cox.net= > wrote:

<= span style=3D"FONT-SIZE: 12pt"> 

<= span style=3D"FONT-SIZE: 12pt">So, what's the most reliable method of g= etting the big fat wire from the battery (in the tail) to the essential bus= at the panel?  I had initially connected this wire directly to the ba= ttery (unfused), but later added the big 60 amp fuse.  Being a fibergl= ass plane, would a carefully run unfused wire be preferrable to a fused wir= e?  Is a relay more reliable than a big fuse?  Would a solid-stat= e relay be even better? =20

Fuses are very reliable, certai= nly more than a relay.  I didn't put my engine critical "bus" (actuall= y a 6 place fuse holder) at the panel.  I preferred to put that 'bus' = near the batteries, and then ran the smaller wires (each now protected) to = the switches on the panel, and on to the engine. Things are then fault tole= rant because blowing any one fuse doesn't keep the engine from running.&nbs= p; Also avoids a large noisy wire at the panel; which can be more of an RF = issue than the distributed smaller wires.

 

Depending on where your large w= ire (10 or 12 AWG?) has to run, with no risk of abrasion or shorting to oth= er wires it can be fine unprotected.  Every case is different.=20

 

I have a #2 wire running from t= he contactor near the battery in front to the starter on the engine in the = rear.  No fuse or breaker is appropriate for that.

 

I assume you wiring is all in p= lace, and not a work in progress.

 

Al G

<= span style=3D"FONT-SIZE: 12pt"> 

<= span style=3D"FONT-SIZE: 12pt">Mark S.

 

On 12/4/0= 7, Al Gietzen = < ALVentures@cox.net> wrote:

 

That's what I did... Flight Critical bus i= s always hot, although I did add a 60 amp fuse back near the battery. =
 Mark S.=20

I= s that fuse in the only power path to the engine critical bus?  I thin= k fuses are a very reliable way to go; but for this application they are sy= nonymous with "fault tolerance".  IOW, blowing one fuse does= not shut you down.  Actually, I would also apply the fault tolerance = idea to the use of breakers for critical items.=20

O= ne of the nice things about our setup is we have dual plugs, dual injectors= , dual controllers, and dual fuel pump. That gives you the potential for ve= ry high reliability - a failure of any one of the pair does not put you on = the ground.  I chose to use a separate circuit to each to gain failure= tolerance. Each circuit is protected with a fuse, and the fuse holder is p= owered directly from both batteries with isolation diodes so even a battery= failure doesn't stop the engine.=20

W= ires are cheap and light and very reliable. Fuses cost only pennies, so cha= nge them out and check the contacts every annual, or every 6 months if you = feel like it. I like that better than a breaker that has been in the panel = for 10 years. Fault tolerance =3D high reliability. (I almost said =96 fuse= s and fault tolerance, but I don't want to start that fuses vs breakers= discussion again=20 J<= font face=3D"Verdana" color=3D"blue" size=3D"2"> )

F= WIW,

A= l

 <= /span>

<= span style=3D"FONT-SIZE: 12pt"> 


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