---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Tue 03/07/17: 8 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 04:53 AM - Z-17 battery/ alternator switch (Jeff Point) 2. 05:11 AM - Re: Z-17 battery/ alternator switch (Rene Felker) 3. 05:49 AM - Re: Z-17 battery/ alternator switch (user9253) 4. 08:25 AM - Switch Panel Layout (rvtach) 5. 08:31 AM - Re: Switch Panel Layout (rvtach) 6. 08:48 AM - Re: Re: Z-17 battery/ alternator switch (Robert L. Nuckolls, III) 7. 03:03 PM - Re: Re: Z-17 battery/ alternator switch (iiNet) 8. 06:14 PM - Re: Z-17 battery/ alternator switch (user9253) ________________________________ Message 1 _____________________________________ Time: 04:53:42 AM PST US From: Jeff Point Subject: AeroElectric-List: Z-17 battery/ alternator switch All, I'm building a simple day/ VFR airplane with Z-17 as the basis for my electric system. I noticed that the battery/ alternator switch is a two-throw switch wired as "Off-battery-alternator", presumably to be able to start on battery power and bring the alternator online once the engine is running. Other drawings (Z-13/8 for example) use a simple single-throw switch to bring battery and alternator on together. I've flown with a Z-13-type system in my RV-6 for 13 years so I have faith in it. Why the different switch design in Z-17? Is there something about the PM dynamo alternator that requires it to be off during engine start? Is it because Z-17 doesn't use a master contactor? Would there be any harm in starting with the PM alternator online? Thanks Jeff Point Milwaukee WI ________________________________ Message 2 _____________________________________ Time: 05:11:29 AM PST US From: "Rene Felker" Subject: RE: AeroElectric-List: Z-17 battery/ alternator switch I always thought that the reason for split switches, etc, was so you could turn off the alternator without turning off the battery. I always start with the alternator on.......just my 2 cents. -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Jeff Point Sent: Tuesday, March 7, 2017 5:50 AM Subject: AeroElectric-List: Z-17 battery/ alternator switch All, I'm building a simple day/ VFR airplane with Z-17 as the basis for my electric system. I noticed that the battery/ alternator switch is a two-throw switch wired as "Off-battery-alternator", presumably to be able to start on battery power and bring the alternator online once the engine is running. Other drawings (Z-13/8 for example) use a simple single-throw switch to bring battery and alternator on together. I've flown with a Z-13-type system in my RV-6 for 13 years so I have faith in it. Why the different switch design in Z-17? Is there something about the PM dynamo alternator that requires it to be off during engine start? Is it because Z-17 doesn't use a master contactor? Would there be any harm in starting with the PM alternator online? Thanks Jeff Point Milwaukee WI ________________________________ Message 3 _____________________________________ Time: 05:49:03 AM PST US Subject: AeroElectric-List: Re: Z-17 battery/ alternator switch From: "user9253" > Would there be any harm in starting with the PM alternator online? No, in fact that is common practice and is recommended. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=466963#466963 ________________________________ Message 4 _____________________________________ Time: 08:25:02 AM PST US Subject: AeroElectric-List: Switch Panel Layout From: "rvtach" Hi- Some time ago Bob published a sample switch panel layout that showed switches and labels. I generally copied one of the examples and am now ready to label my panel but I can't find Bob's drawing. I have searched the archives and found a link that I think used to put to the drawing but now it just takes me to the Aeroelectric website and I can't find the drawing there either. I could come up with my own label wording etc but as usual what Bob showed was very succinct, clear and concise and they looked really nice. If someone could help point me in the right direction to find this I would be very grateful. Thanks! -------- Jim McChesney Tucson, AZ RV-7A Finishing Kit Read this topic online here: http://forums.matronics.com/viewtopic.php?p=466967#466967 ________________________________ Message 5 _____________________________________ Time: 08:31:36 AM PST US Subject: AeroElectric-List: Re: Switch Panel Layout From: "rvtach" Ok, never mind. After posting this I went back one more time and immediately found what I was looking for. Go figure. I have spent 2+ hours looking for this. Sorry to take the groups time. Here's the link: http://www.aeroelectric.com/Reference_Docs/Misc_PDF/Switches.pdf -------- Jim McChesney Tucson, AZ RV-7A Finishing Kit Read this topic online here: http://forums.matronics.com/viewtopic.php?p=466968#466968 ________________________________ Message 6 _____________________________________ Time: 08:48:22 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Z-17 battery/ alternator switch At 07:46 AM 3/7/2017, you wrote: > > > > Would there be any harm in starting with the PM alternator online? >No, in fact that is common practice and is recommended. Actually, it's six-of-on, half-dozen-of-the-other. A bit of history: The first electrical systems to be installed on aircraft used generators . . . just like the ones on cars, tractors and trucks. These were simply shunt wound, DC MOTORS being PUSHED with mechanical energy into the shaft such that they became GENERATORS. They required rather sophisticated regulators that not only maintained the target bus voltage but limited output current (to prevent commutator and armature over-heat) and provided reverse current disconnect so that a NON rotating generator did not revert to it's roots as a motor and run the battery down after the engine stopped. These electro-mechanical analogs to modern electronics are exceedingly clever creations of the era. Emacs! Generators were self-exciting (meaning that they would come on line with a simple input of mechanical energy (engine running) and flipping the field supply switch to ON. Further, they would run well without a battery on line. Modern starter-generators on turbine aircraft retain traits of their ancestors and they too run well without having a battery on line. Hence, aircraft with any form of generator will generally have BOTH battery master and generator control switches. Interestingly enough, the Beech Bonanza STILL has independent BATTERY and ALTERNATOR switches . . . which is another story. When we started putting alternators on TC aircraft (mid 60s) it was discovered that (1) the alternators did not self excite at ramp idle rpm and (2) voltage regulation dynamics were not as comfortable as the generators being replaced. Cessna (and others) were 'upgrading' the panel styles to incorporate rocker switches. Cessna approached Carling to supply a split-rocker switch that would (1) provide battery and alternator control in one device, (2) allow battery only operations and (3) prevent alternator only operations. http://tinyurl.com/zbo3yg6 Nowadays, many if not most alternators will self excite at less than cruise rpms . . . voltage regulation dynamics are improved too . . . so it is less problematic to consider alternator-only ops. Given the inherent reliability of the artfully maintained battery, there is really no demontrable value in planning to accommodate alternator only ops . . . but it is not outside the realm of possibility . . . indeed, the POH for Bonanzas (and I think Barons) speak to this option. Now, how about the differences between the single-throw and three-throw options depicted in the Z-figures? EITHER approach is perfectly satisfactory. The single throw switch prevents alternator-only ops while a PULLABLE circuit breaker offers a means for breaking alternator field supply for battery-only ops on the ground. The three throw switch emulates the split-rocker switch functionality and design goals adopted by the TC aircraft guys . . . a philosophy that persists to this day. MYTHBUSTING: In some circles it has been believed and taught that turning an alternator ON/OFF while the engine is running is a bad thing . . . puts lots of stresses on shafts, shear couplings, gear trains, etc. etc. It has also been reputed to induce radio zapping transients into the electrical system. In a word . . . HOGWASH. I've spent hundreds of hours evaluating alternator/battery/ airplane symbiosis in both in the lab and on airplanes. I've conducted, witnessed and instrumented hundreds of switching combinations of battery, alternators and system loads under the full constellation of conditions. There is no foundation in physics or practice for the admonition to start the engine with the alternator switch ON. Leaving it OFF does relive the battery of about 3A of parasitic load during cranking . . . a trivial concern. The short answer: Use which ever MASTER DC PWR switch philosophy floats ur boat. Either will perform as advertised. Bob . . . ________________________________ Message 7 _____________________________________ Time: 03:03:47 PM PST US Subject: Re: AeroElectric-List: Re: Z-17 battery/ alternator switch From: iiNet Why is it recommended Joe? Kind Regards, Stu Sent from my iPhone > On 8 Mar 2017, at 00:46, user9253 wrote: > > > >> Would there be any harm in starting with the PM alternator online? > No, in fact that is common practice and is recommended. > > -------- > Joe Gores > > > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=466963#466963 > > > > > > > > > ________________________________ Message 8 _____________________________________ Time: 06:14:07 PM PST US Subject: AeroElectric-List: Re: Z-17 battery/ alternator switch From: "user9253" Recommended so that the pilot does not forget to turn it on. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=466988#466988 ------------------------------------------------------------------------------------- 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.