Return-Path: Received: from fed1rmmtao11.cox.net ([68.230.241.28] verified) by logan.com (CommuniGate Pro SMTP 4.2b5) with ESMTP id 142883 for flyrotary@lancaironline.net; Mon, 07 Jun 2004 11:52:58 -0400 Received: from BigAl ([68.107.116.221]) by fed1rmmtao11.cox.net (InterMail vM.6.01.03.02 201-2131-111-104-20040324) with ESMTP id <20040607155225.BTNQ26971.fed1rmmtao11.cox.net@BigAl> for ; Mon, 7 Jun 2004 11:52:25 -0400 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: LS1 Coils - amp draw? Date: Mon, 7 Jun 2004 08:52:28 -0700 Message-ID: <000001c44ca7$6f396ba0$6400a8c0@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01C44C6C.C2DA93A0" 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 V6.00.2800.1165 This is a multi-part message in MIME format. ------=_NextPart_000_0001_01C44C6C.C2DA93A0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Subject: [FlyRotary] Re: LS1 Coils - amp draw? =20 =20 ----- Original Message -----=20 From: Al Gietzen =20 To: Rotary motors in aircraft =20 Sent: Sunday, June 06, 2004 2:35 PM Subject: [FlyRotary] Re: LS1 Coils - amp draw? =20 =20 The peak current draw on the LS1 coils is 9A EACH. This can happen on startup before the EC2 can compute the proper dwell time. Average amps = is much lower during normal operation. =20 =20 Prior to any discussion of fuses vs CBs; this issue needs some clarification. Is it possible for more than one coil to be drawing this level of current at the same time? I have 6 coils on my 20B; three on = each circuit with a 16 AWG wire. This could be frightening!=20 =20 Al=20 =20 Don't think it is a worry. All can be on for a short time (possibly = long enough to blow a fast acting fuse) but not long enough to heat a 16 ga = wire significantly.=20 Tracy =20 Tracy; =20 Well; the worry is this. Safe wiring practice requires being able to protect the wire, especially if it is in a bundle or close proximity = with other wires, against any failure which would overload the wire. Running = the numbers says that the maximum safe current for a 16 awg wire is 15 amps. = If I interpret you correctly; it is possible for my coil power lead to have = to carry 27 amps (for 3 coils) for a short time, which would trip a = breaker, or blow a fuse. Under these conditions one can not properly protect the = wire against a potential short - unless a much larger wire is used. My wires = run in a wiring duct, which isn't exactly a bundle, but the analysis says = for 27 amps in a bundle you need about a #10 wire. =20 Further; I went to great lengths to maintain the redundancy that you = also strived for in the ECU with the dual controllers and the isolation = switches. I have the engine critical bus connected to the dual battery system, and isolated by 40 amp diodes. I think you're suggesting that it's possible = for the coils to momentarily draw 54 amps (6 x 9), plus pump and injectors; maybe up to nearly 70 amps. Ain't gonna work. =20 So what am I misunderstanding here, or how do we get around this? Under what temporary condition can this high current exist? Is there an operational sequence to avoid this possible condition? =20 Thanks, =20 Al =20 ------=_NextPart_000_0001_01C44C6C.C2DA93A0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Message

Subject: [FlyRotary] Re: LS1 Coils - amp draw?

 

 <= /font>

=

----- Original Message -----

From: Al Gietzen

Sent: = Sunday, June 06, 2004 = 2:35 PM

Subject: [FlyRotary] Re: LS1 Coils - amp draw?

 <= /font>

 

The peak current draw on the LS1 coils is 9A EACH.   This can = happen on startup before the EC2 can compute the proper dwell time.  Average = amps is much lower during normal operation.

 

 

Prior to any discussion of fuses vs CBs; this issue needs some clarification.  Is it possible for more than one coil to be drawing this level of = current at the same time?  I have 6 coils on my 20B; three on each circuit = with a 16 AWG wire.  This could be frightening!

 

Al =

 

Don't think it is a worry.   All can be on for a short time = (possibly long enough to blow a fast acting fuse) but not long enough to heat a 16 ga = wire significantly.=  

Tracy

 

Tracy;

 

Well; the worry is this.  = Safe wiring practice requires being able to protect the wire, especially if = it is in a bundle or close proximity with other wires, against any failure which = would overload the wire.  Running the numbers says that the maximum safe = current for a 16 awg wire is 15 amps.  If I interpret you correctly; it is possible for my coil power lead to have to carry 27 amps (for 3 coils) = for a short time, which would trip a breaker, or blow a fuse.  Under = these conditions one can not properly protect the wire against a potential = short – unless a much larger wire is used.  My wires run in a wiring duct, = which isn’t exactly a bundle, but the analysis says for 27 amps in a = bundle you need about a #10 wire.

 

Further; I went to great lengths = to maintain the redundancy that you also strived for in the ECU with the = dual controllers and the isolation switches.  I have the engine critical bus = connected to the dual battery system, and isolated by 40 amp diodes.  I think = you’re suggesting that it’s possible for the coils to momentarily draw 54 = amps (6 x 9), plus pump and injectors; maybe up to nearly 70 amps.  Ain’t gonna = work.

 

So what am I misunderstanding = here, or how do we get around this?  Under what temporary condition can this = high current exist?  Is there an operational sequence to avoid this = possible condition?

 

Thanks,

 

Al

 

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