X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 1 [X] Return-Path: Sender: To: lml Date: Fri, 22 Dec 2006 23:16:49 -0500 Message-ID: X-Original-Return-Path: Received: from mx1.pshift.com ([216.57.116.6] verified) by logan.com (CommuniGate Pro SMTP 5.1.3) with ESMTP id 1703006 for lml@lancaironline.net; Fri, 22 Dec 2006 21:41:30 -0500 Received-SPF: none receiver=logan.com; client-ip=216.57.116.6; envelope-from=colyncase@earthlink.net Received: from ccaselt (unverified [216.57.118.129]) by mx1.pshift.com (Vircom SMTPRS 4.35.480.0) with SMTP id for ; Fri, 22 Dec 2006 21:40:31 -0500 Received-SPF: none (mx1.pshift.com: domain of colyncase@earthlink.net does not designate any permitted senders) X-Modus-BlackList: 216.57.118.129=OK;colyncase@earthlink.net=OK X-Modus-RBL: 216.57.118.129=Excluded X-Modus-Trusted: 216.57.118.129=NO X-Original-Message-ID: <078f01c7263b$b2aa0000$0302a8c0@nvidia.com> From: "colyncase on earthlink" X-Original-To: "Lancair Mailing List" References: Subject: Re: [LML] Re: System level reliability X-Original-Date: Fri, 22 Dec 2006 18:40:18 -0800 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_078C_01C725F8.A0DE0350" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2869 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2962 This is a multi-part message in MIME format. ------=_NextPart_000_078C_01C725F8.A0DE0350 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Mike said, I think the dual bus, crossfeed setup is excellent.=20 I reviewed my system with an EE this morning. This guy is also a pilot = and experienced a night IMC total electrical failure in a baron. He pointed out a couple negatives to the "columbia" style dual bus with = cross-feed. 1) if the primary alternator shorts there is no way to run anything on = your primary bus because any alternate source will also see the short. 2) if anything on the primary bus shorts in such a way that you can't = isolate it with a breaker, your xfeed is similarly useless. So having an xfeed in some circumstances can lead you to wiping out your = backup power source. He suggested isolating the primary load bus so that it doesn't share the = fate of the primary alternator. One way would be with a switch that can choose either power source (primary or backup) at the primary load = bus. Another way to would be to diode feed it (with much bigger diodes) similarly to how the essential bus is shown on the Columbia. Colyn ------=_NextPart_000_078C_01C725F8.A0DE0350 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Mike said,

I think the dual bus, crossfeed setup is = excellent.

I reviewed my system with an EE this morning. This guy is = also a=20 pilot and experienced a night IMC total electrical failure in a = baron.

He pointed out a couple negatives to the "columbia" style dual bus = with=20 cross-feed.

1) if the primary alternator shorts there is no way to run anything = on your=20 primary bus because any alternate source will also see the short.

2) if anything on the primary bus shorts in such a way that you = can't=20 isolate it with a breaker, your xfeed is similarly useless.

So having an xfeed in some circumstances can lead you to wiping out = your=20 backup power source.

He suggested isolating the primary load bus so that it doesn't = share the=20 fate of the primary alternator. One way would be with a switch = that

can choose either power source (primary or backup) at the = primary load=20 bus. Another way to would be to diode feed it (with much bigger=20 diodes)

similarly to how the essential bus is shown on the Columbia.

Colyn

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