X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fed1rmmtao02.cox.net ([68.230.241.37] verified) by logan.com (CommuniGate Pro SMTP 4.3c5) with ESMTP id 930725 for flyrotary@lancaironline.net; Tue, 03 May 2005 00:24:54 -0400 Received-SPF: none receiver=logan.com; client-ip=68.230.241.37; envelope-from=ALVentures@cox.net Received: from BigAl ([68.7.14.39]) by fed1rmmtao02.cox.net (InterMail vM.6.01.04.00 201-2131-118-20041027) with ESMTP id <20050503042407.GIIY22430.fed1rmmtao02.cox.net@BigAl> for ; Tue, 3 May 2005 00:24:07 -0400 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: ECU power - was fuses vs breakers Date: Mon, 2 May 2005 21:24:18 -0700 Message-ID: <000501c54f97$f8ffb210$6400a8c0@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0006_01C54F5D.4CA0DA10" 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 V6.00.2900.2180 This is a multi-part message in MIME format. ------=_NextPart_000_0006_01C54F5D.4CA0DA10 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable By the way, Tracy's ECU can be powered through two different ways. = The original intended way and a sneak circuit way through the powering of = the injectors. I found this out when I wired a switch to the EC2 CPU power terminal. When I turned off the switch the EC2 did not turn off because = the injectors still had voltage and there was a sneak circuit that kept the = EC2 with DC power. Tracy may have eliminated that sneak circuit in later versions - but its there on mine. =20 Yes; I had noted that on mine as well - at least that the light would = stay on if the injectors were on. I don't think I verified whether the = engine would continue running with the ECU off. =20 Al=20 =20 ----- Original Message -----=20 From: Al Gietzen =20 To: Rotary motors in aircraft=20 Sent: Monday, May 02, 2005 2:28 PM Subject: [FlyRotary] fuses vs circuit breakers - or something else =20 =20 I think the key point in this discussion is not so much fuses vs circuit breakers; but that we follow the philosophy of not having single point failures in the flight critical systems. The rotary engine has dual plugs/rotor, most induction systems have two injectors/rotor; Tracy's = ECU has dual units built in (although unfortunately, common input power = point); and most of us are using dual fuel pumps. Separate and independent = feeds to each of these can eliminate single point failures.=20 =20 The choice of fuse or breaker is as much opinion as it is technical = fact, and a winning argument for either in our airplanes isn't going to = happen. There are advantages and disadvantages to both. =20 I have separate and independent power feeds to each set of coils, to = each set of injectors, to each pump, and to the ECU. I have a mix of = breakers and fuses. I happened to choose fuses (blade type) for the injectors, = coils, and pumps somewhat along the lines of Jim's argument - I can protect = those wires with 15 amp fuses. The ECU has one circuit through a breaker, and = one fused. These circuits are as simple and direct as possible. Battery - = to fuse - to disable switch - to component. No intermediate contactors or connectors to fail. Of course I also have two batteries. =20 Fuses, of course, cost nothing, and can be changed out on a whim; so = there is no reason for them ever to be old and fatigued. CB's are a thermal switch; a bit more complex, expensive and generally difficult to change, = so they are likely to get old. That will be the only point I will make = either way. =20 You choose; CB or fuse. I think that choice is less important than how = you design and execute your circuit. =20 FWIW, =20 Al =20 =20 =20 =20 -----Original Message----- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Russell Duffy Sent: Monday, May 02, 2005 8:21 AM To: Rotary motors in aircraft Subject: [FlyRotary] Re: finally changed to fuses vs circuit breakers=20 =20 You've been working field service long enough to know that fuses go bad, too. They de-solder; they break due to vibration; the ends corrode and lose connectivity. I've seen this happen on cheesy fuse holders. I have never seen, or = heard of it happening on an automotive fuse. Now, don't start telling me = stories of some crappy old car that had rats in the fuse holder, because that = ain't comparable. =20 =20 I have items like fuel pumps separately fused, and to the wiring rating, = so they should never blow unless there's a good reason. Items like the = EC-2 are directly tied to power, via two attachment points. This is how = Tracy recommends it, because the controller will be it's own fuse. =20 =20 If I had the panel space, and believed CB's offered any significant = benefit, I wouldn't care about the cost and weight. =20 =20 Gotta go pick up my new company van, and replace a switch in Mobile. =20 Rusty (discussion for entertainment only) =20 =20 =20 ------=_NextPart_000_0006_01C54F5D.4CA0DA10 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Message

  By the way, = Tracy's ECU can be powered through two different ways.  The original intended way = and a sneak circuit way through the powering of the injectors.  I found = this out when I wired a  switch to the EC2 CPU power terminal.  When I = turned off the switch the EC2 did not turn off because the injectors still had = voltage and there was a sneak circuit that kept the EC2 with DC power.  = Tracy may  have eliminated that sneak circuit in later versions - but its = there on mine.

 

Yes; I had noted that on mine as = well – at least that the light would stay on if the injectors were on.  I = don’t think I verified whether the engine would continue running with the ECU = off.

 

Al

 

=

----- Original Message = -----

From: Al = Gietzen

Sent: Monday, May 02, 2005 2:28 PM

Subject: [FlyRotary] fuses vs circuit breakers - or something else

 

 

I think the key point in this discussion is not so much fuses vs circuit breakers; but that we follow the philosophy of not having single point = failures in the flight critical systems.  The rotary engine has dual = plugs/rotor, most induction systems have two injectors/rotor; Tracy’s ECU = has dual units built in (although unfortunately, common input power point); and = most of us are using dual fuel pumps.  Separate and independent feeds to = each of these can eliminate single point failures.

 

The choice of fuse or breaker is as much opinion as it is technical fact, = and a winning argument for either in our airplanes isn’t going to = happen.  There are advantages and disadvantages to both.

 

I have separate and independent power feeds to each set of coils, to each = set of injectors, to each pump, and to the ECU.  I have a mix of breakers = and fuses. I happened to choose fuses (blade type) for the injectors, coils, = and pumps somewhat along the lines of Jim’s argument – I can = protect those wires with 15 amp fuses.  The ECU has one circuit through a = breaker, and one fused.  These circuits are as simple and direct as = possible. Battery - to fuse - = to disable switch – to component.  No intermediate contactors or = connectors to fail.  Of course I also have two batteries.

 

Fuses, of course, cost nothing, and can be changed out on a whim; so there is = no reason for them ever to be old and fatigued. CB’s are a thermal = switch; a bit more complex, expensive and generally difficult to change, so they = are likely to get old.  That will be the only point I will make either = way.

 

You choose; CB or fuse.  I think that choice is less important than how = you design and execute your circuit.

 

FWIW,

 

Al

 

 

 

 

-----Original = Message-----
From: Rotary motors in = aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Russell Duffy
Sent: Monday, May 02, 2005 8:21 = AM
To: Rotary motors in = aircraft
Subject: [FlyRotary] Re: = finally changed to fuses vs circuit breakers

 

You've been working field service long enough = to know
that fuses go bad, too.  They de-solder; they break due to
vibration; the ends corrode and lose connectivity.

I've seen this = happen on cheesy fuse holders.  I have never seen, or heard of it = happening on an automotive fuse.  Now, don't start telling me stories of = some crappy old car that had rats in the fuse holder, because that ain't comparable.  

 

I have items like = fuel pumps separately fused, and to the wiring rating, so they should never = blow unless there's a good reason.  Items like the EC-2 = are directly tied to power, via two attachment points.  This is how = Tracy = recommends it, because the controller will be it's own = fuse.  

 

If I had the = panel space, and believed CB's offered any significant benefit, I wouldn't care about = the cost and weight.  

 

Gotta go pick up = my new company van, and replace a switch in Mobile.

 

Rusty (discussion = for entertainment only)

 

 

 

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