---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Fri 07/23/10: 3 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 09:31 AM - Re: Electrical System Schematic Review (jonlaury) 2. 12:12 PM - Re: Re: Electrical System Schematic Review (Robert L. Nuckolls, III) 3. 03:00 PM - Re: Electrical System Schematic Review (user9253) ________________________________ Message 1 _____________________________________ Time: 09:31:41 AM PST US Subject: AeroElectric-List: Re: Electrical System Schematic Review From: "jonlaury" Joe, thanks. The correction is on Rev. B that I'll post this morning. I have one other question and then I think I've got this knocked. >From the Ebus alt feed contactor to the Ebus, there is a fusible link called for. My Ebus is fused at 30a at the battery bus and will run at about 20-24 amps and I'm using an 8AWG wire to keep temps down so the fuse link would be a 12AWG. I think that I will put a 40a at the batt bus for the 8AWG protection and to give some head room for the Ebus. Would it be a better design to use a 30a ANL current limiter in place of the 12AWG Fuselink? John Read this topic online here: http://forums.matronics.com/viewtopic.php?p=306095#306095 ________________________________ Message 2 _____________________________________ Time: 12:12:12 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Electrical System Schematic Review At 11:29 AM 7/23/2010, you wrote: > >Joe, thanks. > >The correction is on Rev. B that I'll post this morning. > >I have one other question and then I think I've got this knocked. > > >From the Ebus alt feed contactor to the Ebus, there is a fusible > link called for. My Ebus is fused at 30a at the battery bus and > will run at about 20-24 amps and I'm using an 8AWG wire to keep > temps down so the fuse link would be a 12AWG. I think that I will > put a 40a at the batt bus for the 8AWG protection and to give some > head room for the Ebus. Would it be a better design to use a 30a > ANL current limiter in place of the 12AWG Fuselink? I thing the concept for an E-bus has run off into the weeds. The original idea for the e-bus was to craft a plan-b that offered an option for a system that would take you comfortably to airport of intended destination . . . battery only. When vacuum pumps started dropping like flies, we reasoned that e-bus loads could take a jump by supplementing a battery with an 8A engine driven power source. Even then, sizing of continuous operating loads during an alternator failure event was still LIMITED. A modicum of planning was necessary to craft the optimal plan-b. Your aux alternator is large enough to run all normal operating loads of 99% of all OBAM aircraft flying. Hence, the notion of segmenting electrical loads into "normal" and "endurance" camps for the purpose optimizing battery-only operations is curious. With a 40A aux alternator one is inclined to run a battery until it croaks . . . If you're not running a battery maintenance program designed to maintain some required reserve capacity, then the whole idea of an e-bus is moot. Further, the notion of battery-only operations for a electrically dependent engine under the best of conditions is a scenario most system designers would rather not contemplate. I'll suggest you stand back and review the big picture. Consider something like Figure Z-12 and no e-bus. This is how hundreds of TC aircraft are configured to integrate robust alternators into the electrical system. Before you get deeply distracted with the details of what fuse or diode goes where, you need to Work through anticipated failure modes and see first how ARCHITECTURE mitigates those failures. Keep in mind that crafting a preventative maintenance plan unique to your needs marches hand-in-hand with architecture and sizing of hardware. I think you'll find that a Z-12 basis for your proposed system is simpler, easier to operate, and better suited to an airplane with an electrically dependent engine. Bob . . . ________________________________ Message 3 _____________________________________ Time: 03:00:29 PM PST US Subject: AeroElectric-List: Re: Electrical System Schematic Review From: "user9253" > Would it be a better design to use a 30a ANL current limiter in place of the 12AWG Fuselink? Short answer is no. The long answer is that I agree with Bob that the electrical system is much more heavy duty than most airplanes. If you are sure that you need this redundancy for IFR over hostile terrain or whatever, then this is what I would do. Get rid of the fuse at the battery bus and mount the E-Bus relay as close to the battery as possible and use a 14awg wire (fuselink) between the battery bus and the relay. Put a 30amp ANL at the relay in series with 10awg to the E-bus. I am not saying that this is the right way to do it, just the way that I would do it. Your way will work too. Keep in mind that it will difficult to blow a 40amp ANL fuse or even a 30 amp for that matter. Use double insulation where the wire passes though the firewall or bulkheads and take care with the installation and a fuse will never blow, nor will there be smoke. I am heading for OSH. Joe -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=306116#306116 ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.