X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from ms-smtp-02.southeast.rr.com ([24.25.9.101] verified) by logan.com (CommuniGate Pro SMTP 5.1.0) with ESMTP id 1490852 for flyrotary@lancaironline.net; Sat, 21 Oct 2006 08:43:35 -0400 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.101; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-098-062.carolina.res.rr.com [24.74.98.62]) by ms-smtp-02.southeast.rr.com (8.13.6/8.13.6) with SMTP id k9LChEvu018532 for ; Sat, 21 Oct 2006 08:43:15 -0400 (EDT) Message-ID: <000901c6f50e$7c60e530$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Fuse Ratings for Wiring?? Date: Sat, 21 Oct 2006 08:43:18 -0400 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 X-Virus-Scanned: Symantec AntiVirus Scan Engine Yes, Bill, that is what I understand as well. BUT, if you are fused for the equipment load, the wiring is automatically protected (in a proper design). In fact, by using a smaller rated fuse (designed just to protect the equipment rather than the wiring) you are even better ensuring that the wiring won't carry a dangerous load and catch fire. So again, I can see no rational reason for fusing to protect the wire rather than a lower rated fuse/CB to protect the equipment (regardless of whether it actually protects the equipment). But, then I've never been accused of being the brightest turnip on the tomato truck. Ed ----- Original Message ----- From: "Bill Schertz" To: "Rotary motors in aircraft" Sent: Friday, October 20, 2006 11:24 PM Subject: [FlyRotary] Re: Fuse Ratings for Wiring?? > 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/ > > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ >