X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fed1rmmtao102.cox.net ([68.230.241.44] verified) by logan.com (CommuniGate Pro SMTP 5.2c1) with ESMTP id 2555997 for flyrotary@lancaironline.net; Tue, 04 Dec 2007 15:21:32 -0500 Received-SPF: none receiver=logan.com; client-ip=68.230.241.44; envelope-from=alventures@cox.net Received: from fed1rmimpo03.cox.net ([70.169.32.75]) by fed1rmmtao102.cox.net (InterMail vM.7.08.02.01 201-2186-121-102-20070209) with ESMTP id <20071204202054.KZMR16731.fed1rmmtao102.cox.net@fed1rmimpo03.cox.net> for ; Tue, 4 Dec 2007 15:20:54 -0500 Received: from BigAl ([72.192.143.193]) by fed1rmimpo03.cox.net with bizsmtp id LkLs1Y00J4AaN600000000; Tue, 04 Dec 2007 15:20:52 -0500 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: circuit breakers Date: Tue, 4 Dec 2007 12:21:04 -0800 Message-ID: <000001c836b3$323b1d80$6401a8c0@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01C83670.2417DD80" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3198 This is a multi-part message in MIME format. ------=_NextPart_000_0001_01C83670.2417DD80 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable =20 That's what I did... Flight Critical bus is always hot, although I did = add a 60 amp fuse back near the battery. =20 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 = you down. Actually, I would also apply the fault tolerance idea to the use = of breakers for critical items.=20 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 = 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 powered directly from both batteries with isolation diodes so = even a battery failure doesn't stop the engine.=20 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 = - fuses and fault tolerance, but I don't want to start that fuses vs = breakers discussion again:-)) FWIW, Al =20 ------=_NextPart_000_0001_01C83670.2417DD80 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

 

That's what I did... Flight Critical bus is = always hot, although I did add 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 you down.  Actually, I would = also apply the fault tolerance idea to the use of 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 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 powered directly from both batteries with isolation = diodes so even 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 – fuses and fault tolerance, but I = don’t want to start that fuses vs breakers discussion againJ)=

FWIW,

Al

 

------=_NextPart_000_0001_01C83670.2417DD80--