X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 1 [X] Return-Path: Sender: To: lml Date: Wed, 06 Dec 2006 01:44:48 -0500 Message-ID: X-Original-Return-Path: Received: from relay2.av-mx.com ([137.118.16.124] verified) by logan.com (CommuniGate Pro SMTP 5.1.3) with ESMTP id 1645041 for lml@lancaironline.net; Tue, 05 Dec 2006 22:23:02 -0500 Received-SPF: pass receiver=logan.com; client-ip=137.118.16.124; envelope-from=pinetownd@volcano.net X-Virus-Scan-Time: 0 Received: from [137.118.16.61] (HELO mx0.av-mx.com) by relay2.av-mx.com (CommuniGate Pro SMTP 4.2.10) with SMTP id 506424810 for lml@lancaironline.net; Tue, 05 Dec 2006 22:22:41 -0500 Received: (qmail 22112 invoked from network); 6 Dec 2006 03:22:40 -0000 Received: from 65-172-208-30.du.volcano.net (HELO DennisDell) (pinetownd@volcano.net@65.172.208.30) by 0 with SMTP; 6 Dec 2006 03:22:40 -0000 X-CLIENT-IP: 65.172.208.30 X-CLIENT-HOST: 65-172-208-30.du.volcano.net X-Original-Message-ID: <009401c718e5$c3bb2df0$6601a8c0@DennisDell> From: "Dennis Johnson" X-Original-To: Subject: Self-Excitation X-Original-Date: Tue, 5 Dec 2006 19:22:30 -0800 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0091_01C718A2.B4F0FF90" 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_0091_01C718A2.B4F0FF90 Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable Greetings, The kind of self-excitation I'm talking about refers to backup = alternators and has nothing to do with looking at certain web sites "for = education purposes only." =20 The issue is that alternators typically require an outside source of = electricity to bring themselves on line before they can start making = electricity. In the unlikely event that a battery post breaks off, for = example, totally disabling the battery, a backup alternator could not be = brought on line unless it is self-exciting. Also, although it is = unrelated to self-excitation, there is a good chance that the primary = alternator would stop functioning reliably once the battery is no longer = connected to it. The SD-8 permanent magnet backup alternator from B&C that I've installed = is reported to function without a battery. I have read, but have not = personally verified, that if the SD-8 is activated once during the = preflight or pre-takeoff checks, it will remain excited throughout the = flight. Therefore, if the battery subsequently fails, the SD-8 will = continue functioning. And for the real worry-warts, Bob Nuckolls has = created a relatively simple wiring schematic that will make the SD-8 = self-exciting even if it had not been activated previously during the = flight. =20 By the way, the type of battery failure I'm talking about here is a = total failure which makes it appear there is no battery connected, not = the more common situation of a "dead" or weak battery. A dead battery, = if it had enough juice to start the airplane at the beginning of the = flight, would probably still have enough to excite and regulate an = alternator, although the alternator's charge rate might be so high that = the alternator's circuit protection could disconnect it. =20 B&C: http://www.bandc.biz/cgi-bin/ez-catalog/cat_display.cgi?17X358218 Bob Nuckolls web page: http://www.aeroelectric.com/ Bob Nuckolls' discussion group: = http://www.matronics.com/Navigator?AeroElectric-List =20 Best, Dennis Johnson, Legacy #257, wings on and hoping for first flight within = two months or so ------=_NextPart_000_0091_01C718A2.B4F0FF90 Content-Type: text/html; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable

Greetings,

The kind of self-excitation I'm talking about refers to backup = alternators=20 and has nothing to do with looking at certain web sites "for education = purposes=20 only."

The issue is that alternators typically require an = outside source of=20 electricity to bring themselves on line before they can start making=20 electricity. In the unlikely event that a battery post breaks off, = for=20 example, totally disabling the battery, a backup alternator could not be = brought=20 on line unless it is self-exciting. Also, although it is unrelated = to=20 self-excitation, there is a good chance that the primary alternator=20 would stop functioning reliably once the battery is no = longer=20 connected to it.

The SD-8 permanent magnet backup alternator from B&C that I've=20 installed is reported to function without a battery. I have read, = but have=20 not personally verified, that if the SD-8 is activated once during = the=20 preflight or pre-takeoff checks, it will remain excited throughout the=20 flight. Therefore, if the battery subsequently fails, the SD-8 = will=20 continue functioning. And for the real worry-warts, Bob Nuckolls=20 has created a relatively simple wiring schematic that = will make=20 the SD-8 self-exciting even if it had not been activated=20 previously during the flight.

By the way, the type of battery failure I'm talking about here = is a=20 total failure which makes it appear there is no battery connected, not = the more=20 common situation of a "dead" or weak battery. A dead = battery, if it=20 had enough juice to start the airplane at the beginning of the flight,=20 would probably still have enough to excite and regulate an = alternator,=20 although the alternator's charge rate might be so high that the = alternator's=20 circuit protection could disconnect it.

B&C: http://www.bandc.biz/cgi-bin/ez-catalog/cat_display.cgi?17X358218

Bob Nuckolls web page: http://www.aeroelectric.com/

Bob Nuckolls' discussion group: http://www.= matronics.com/Navigator?AeroElectric-List =20

Best,

Dennis Johnson, Legacy #257, wings on and hoping for first flight = within=20 two months or so

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