X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from rwcrmhc11.comcast.net ([204.127.192.81] verified) by logan.com (CommuniGate Pro SMTP 5.1.0) with ESMTP id 1490233 for flyrotary@lancaironline.net; Fri, 20 Oct 2006 23:25:18 -0400 Received-SPF: none receiver=logan.com; client-ip=204.127.192.81; envelope-from=wschertz@comcast.net Received: from 7n7z201 (c-24-7-194-231.hsd1.il.comcast.net[24.7.194.231]) by comcast.net (rwcrmhc11) with SMTP id <20061021032459m1100rrif1e>; Sat, 21 Oct 2006 03:25:00 +0000 Message-ID: <002301c6f4c0$7865bf30$e7c20718@7n7z201> From: "Bill Schertz" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Fuse Ratings for Wiring?? Date: Fri, 20 Oct 2006 22:24:50 -0500 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=response Content-Transfer-Encoding: 7bit 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 Ed, I think the objective is to keep from having a wire-induced fire when you get a short to ground. If the insulation rubs and a short develops, you want a fuse/breaker sized to pop before the wire melts and causes a fire. If the equipment has an internal problem, the fuse/breaker isn't going to help save it. Bill Schertz KIS Cruiser # 4045 ----- Original Message ----- From: "Ed Anderson" To: "Rotary motors in aircraft" Sent: Friday, October 20, 2006 5:12 PM Subject: [FlyRotary] Fuse Ratings for Wiring?? > One thing I have never really understood regarding fuses (or CB for > that matter) is - why you would use a fuse/CB with the rating set to > protect the wire!!! If you have a system operating off a power wire, it > is highly likely that the wire will flow much more current than the system > requires by quite a bit. So if you select a fuse or CB rating that > protects the equipment then automatically it will protect the wire. > > However, if you select the rating to protect the wire, the system could > easily fry and the fuse or CB might never trigger. Just one of those > things (wire size) that everybody uses as a guide for selecting the > ratings (Fuse/CB) and yet, it has never made sense to me (and still does > not) {:>) > > I guess IF you put more system load that used more current than a wire > was rated for then a fuse sized for the system would not protect the wire > which could over heat. But, that is simply a bad wiring decision in > selecting too small a wire in the first place. I guess the rational is > better the system fry than the wire - but not certain I buy it. > > I don't really lose sleep over this one - but, I do wonder from time to > time about things we come to accept {:>) > > > Ed > > > > > ----- Original Message ----- > From: "Ed Anderson" > To: "Rotary motors in aircraft" > Sent: Friday, October 20, 2006 5:47 PM > Subject: [FlyRotary] Re: Injector Switches !!! was Re: Powering fuel > injectors > > >> Welcome, Greg. >> >> Yes, there are arguments pro and con about fuses and CB - its about the >> only thing I disagreed with Bob Nuckolls about {:>). Probably influenced >> by my years flying military aircraft - where CB are everywhere and fuses >> no where {:>) >> >> In any case, glad you are now aware of the "disable" switch function >> regarding doubling the fuel flow through on pair of injectors when the >> other is turned off. You can fly easily on one pair - provided it is >> doing double duty with the fuel flow. >> >> Ed >> >> >>> Thanks for that Ed, I am using the EC2 but I hadn't gone through the >>> install of it thoroughly yet and wasn't aware of that mode. I'll make >>> sure that it's done now. >>> >>> I follow what you're saying about breakers instead of fuses and I have >>> to agree, but following the Bob Nuckolls school of wiring means that >>> the fuses/breakers should be no more than 6" to a foot from the power >>> source (battery) and the batteries are behind the rear baggage area and >>> no where near the panel. The argument for the fuses to be near the >>> source of electric power is also valid considering the fuses are there >>> to protect the wiring. >>> >>> Greg >>> >>> >>>> Hi Greg, >>>> >>>> Looks like a good electrical system over all. However, I would not >>>> feel comfortable with fuses in my critical system power line. But, I >>>> see that you are routing two power sources to each switch of your >>>> critical system which means if one fuse blows due to a transit spike, >>>> the other one, hopefully, will not. Again, this is my own personal >>>> bias against fuses in critical systems - there are arguments to the >>>> contrary for sure. >>>> >>>> One thing I did notice, is looking at your injector power switches, I >>>> am not certain if these are meant to be the same as Tracy Crook's >>>> Injector disable switches. If they are (and they may not be), I do not >>>> see the connection that automatically grounds the "cold Start" mode in >>>> the EC2 when either injector pair are disabled (turned off). >>>> >>>> This may be a detail just not shown on the drawing - but it is >>>> crucially important. If the injector power switch does not have the >>>> "cold start" grounding provision, then if you ever switch off one of >>>> the injector pairs, your fuel flow will drop approx by 1/2 half. The >>>> reason is that (with Tracy's recommended switch set up) when you turn >>>> off one pair of injectors , that automatically grounds the "cold start" >>>> pin which causes the EC2 to double the duration of the PW (Pulse Width) >>>> signal to the remaining injector pair. This in turn doubles the amount >>>> of fuel from the active pair of injectors. If the "cold start" is not >>>> activated (by automatic grounding of the cold start pin through a DPDT >>>> switch) when an injector pair is switched off, then the PW signal does >>>> NOT double and the fuel flow through the one injector pair will only be >>>> 1/2 of what the engine needs. >>>> >>>> >>>> Ed >>>> >>>> Ed Anderson >>>> Rv-6A N494BW Rotary Powered >>>> Matthews, NC >>>> eanderson@carolina.rr.com >>>> http://members.cox.net/rogersda/rotary/configs.htm#N494BW >>>> http://www.dmack.net/mazda/index.html >>>> >>>> ----- Original Message ----- >>>> From: "Greg@itmack" >>>> To: "Rotary motors in aircraft" >>>> Sent: Friday, October 20, 2006 3:33 AM >>>> Subject: [FlyRotary] Re: Powering fuel injectors >>>> >>>> >>>>> I'm trying to keep the number of switched down as well, I attached a >>>>> pdf >>>>> with my schematic which is a work in progress for your review. >>>>> >>>>> I have noted that a lot of builders reduce a lot of this complexity by >>>>> just >>>>> hanging everything off 1 or 2 fuses which is fine until a fuse blows >>>>> and >>>>> then everything stops. >>>>> >>>>> Greg RV8 down under >>>>> >>>>> >>>>> >>>>>>I am using Z-19 from the Aeroelectric Connection as a guide for wiring >>>>>> my plane. I would like to power the injectors from the battery buss. >>>>>> Looking at Z-19, do I need to install a complete switch and diode >>>>>> system >>>>>> for the injectors like is done for the fuel pump and ECU, or can I >>>>>> tie >>>>>> on to the fuel pump OR the ECU system after either the switch (add a >>>>>> separate diode) or after one of the diodes? >>>>>> There will be the two DPDT switches to disable the primary and >>>>>> secondary >>>>>> injectors after this connection. >>>>>> My panel is becoming somewhat switch festooned and I would like to >>>>>> keep >>>>>> more switches to a minimum. >>>>>> How have you guys accomplished this? >>>>>> >>>>>> Thanks. >>>>>> Bill B >>>>>> >>>>>> >>>>>> -- >>>>>> Homepage: http://www.flyrotary.com/ >>>>>> Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ >>>>>> >>>>>> >>>>> >>>> >>>> >>>> -------------------------------------------------------------------------------- >>>> >>>> >>>>> -- >>>>> Homepage: http://www.flyrotary.com/ >>>>> Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ >>>>> >>>> >>>> >>>> >>>> -- >>>> Homepage: http://www.flyrotary.com/ >>>> Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ >>>> >>>> >>> >>> >>> -- >>> Homepage: http://www.flyrotary.com/ >>> Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ >>> >> >> >> >> -- >> Homepage: http://www.flyrotary.com/ >> Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ >> > > > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/