---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Wed 04/26/17: 9 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:15 AM - Re: Re: Interesting thread on overvoltage event (Charlie England) 2. 05:17 AM - Re: Interesting thread on overvoltage event (user9253) 3. 06:04 AM - Re: Interesting thread on overvoltage event (rv8ch) 4. 06:42 AM - Re: Re: Interesting thread on overvoltage event (Charlie England) 5. 06:58 AM - Re: Interesting thread on overvoltage event (rv8ch) 6. 07:33 AM - Re: Re: Interesting thread on overvoltage event (Robert L. Nuckolls, III) 7. 07:40 AM - Re: Is a battery contactor really needed? (eschlanser) 8. 01:32 PM - Re: Re: Interesting thread on overvoltage event (Jan de Jong) 9. 03:20 PM - Re: Re: Is a battery contactor really needed? (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 05:15:53 AM PST US From: Charlie England Subject: Re: AeroElectric-List: Re: Interesting thread on overvoltage event There's no difference in how they control the field windings. The big difference *access* to the wire going to the field, by the pilot, for manual control, or the OV module, for automatic control. With external regulation, you can easily interrupt the power feeding the regulator (or even the field wire running from the reg to the alternator's field winding) to remove power from the field winding if the regulator fails. But with an (unmodified) IR alternator, you don't have access to either of those wires (they're both inside the alternator), so if the regulator fails, there's no way to remove power from the field if the regulator fails. The IG terminal on an IR alternator does not supply/remove power from the regulator; it's a 'instruction' terminal that gives the regulator an instruction to turn on or off. If the regulator fails internally, it will likely be unable to comply with the instruction from the IG terminal, so you've lost external control of the alternator. Now the only option is to open the B-lead to keep the OV away from the avionics and battery. Charlie On Wed, Apr 26, 2017 at 1:17 AM, Mickey Coggins wrote: > Thanks for the info. My question is much more "novice". Perhaps I shoul d > describe it a different way. > > Imagine I took the B&C voltage regulator, and made it the size of a dime, > and stuffed it into an Externally regulated alternator. How would that b e > different from what Denso does with their internally regulated alternator ? > > From what I see from the diagrams, the VR simply decides how much V to > send out the F wire. Why would the external give more control? > > Thanks for any clarity! :) > > > =8B > > Mickey Coggins > > On 25 April 2017 at 15:18, Robert L. Nuckolls, III < > nuckolls.bob@aeroelectric.com> wrote: > >> At 04:45 AM 4/25/2017, you wrote: >> >> >> One point that is not clear for me about the internal/external VR >> discussion. I apologize in advance if this has been clarified somewhere >> else and I just missed it. >> >> I don't understand why or how an external voltage regulator can safely >> cut the field using the crowbar method and an internal regulator cannot. >> If I look at the wiring diagrams there does not seem to be a difference. >> Is it just that the external VR is more robust? >> >> Thanks for any clarity you can provide. >> >> >> The externally regulated alternator has NO electronics >> inside . . . just a rudimentary alternator. >> >> [image: Emacs!] >> >> Interrupting the 'field input' line offers total >> control over alternator output. >> >> The internally regulated alternator has solid >> state devices that control alternator output. >> There is no field power input connection, only >> a 'control' connection that talks to the >> electronics. >> >> [image: Emacs!] >> >> There are failure modes INTERNAL to the alternator >> that can cause an over voltage condition . . . a >> * condition not controllable* from outside. >> >> Hence, the legacy preference for externally regulated >> alternators that allow a system integrator to include >> over voltage protection in some form. It doesn't >> have to be the 'crowbar' style . . . there are several >> satisfactory approaches. >> >> The crowbar ov module offers the simplest and most >> robust configuration but it's not intended to displace >> any other demonstrably functioning ov management system. >> >> Bob . . . >> > > ________________________________ Message 2 _____________________________________ Time: 05:17:27 AM PST US Subject: AeroElectric-List: Re: Interesting thread on overvoltage event From: "user9253" > Why would the external give more control? They both have equal control as long as they do not fail. What happens when the voltage regulator fails? How do you shut off the failed regulator to prevent over-voltage? Some internally regulated alternators have an ignition switch terminal that controls the alternator. But that input does not make and break the field circuit. All it does is command the internal regulator to shut off the field. A failed internal regulator could ignore that command and continue to supply excessive field current. The external voltage regulator has easily accessible wires and circuit protection. It is relatively easy to tap into the externally regulated alternator field circuit to add a switch or automatic over-voltage protection. Yes, it is possible to do the same thing with an internally regulated alternator, but it requires much more skill and knowledge which the average homebuilder does not have. The internally regulated alternator gets its field current from within the alternator. The externally regulated alternator gets its field current from the aircraft main power bus. Which is easiest to interrupt? -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=468798#468798 ________________________________ Message 3 _____________________________________ Time: 06:04:41 AM PST US Subject: AeroElectric-List: Re: Interesting thread on overvoltage event From: "rv8ch" user9253 wrote: > The internally regulated alternator gets its field current from within the alternator. > The externally regulated alternator gets its field current from the aircraft main power bus. > Which is easiest to interrupt? This is exactly what triggered my question - in all the Z diagrams it shows the field wire coming from the external VR with no circuit breaker or switch, so it's counting on the good behavior of the VR to cut off the alternator - same as with an internal VR. Why do we have more trust in the external VR than the internal VR? Experience? Known design differences? Perhaps I'm missing something fundamental. Curious minds want to know! :) -------- Mickey Coggins http://www.rv8.ch/ Read this topic online here: http://forums.matronics.com/viewtopic.php?p=468801#468801 ________________________________ Message 4 _____________________________________ Time: 06:42:08 AM PST US From: Charlie England Subject: Re: AeroElectric-List: Re: Interesting thread on overvoltage event On Wed, Apr 26, 2017 at 8:03 AM, rv8ch wrote: > > > user9253 wrote: > > The internally regulated alternator gets its field current from within > the alternator. > > The externally regulated alternator gets its field current from the > aircraft main power bus. > > Which is easiest to interrupt? > This is exactly what triggered my question - in all the Z diagrams it > shows the field wire coming from the external VR with no circuit breaker or > switch, so it's counting on the good behavior of the VR to cut off the > alternator - same as with an internal VR. > > Why do we have more trust in the external VR than the internal VR? > Experience? Known design differences? Perhaps I'm missing something > fundamental. Curious minds want to know! :) > > -------- > Mickey Coggins > http://www.rv8.ch/ > > In the Z diagrams, follow all the wires leaving the regulator. One of them (the A terminal on the generic Ford model) goes through the alternator half of the master switch, to a 5A breaker, which is tied to the main buss. The 5A breaker supplies the regulator with its power. So with external regulators, you're removing the only source of electrons to the field by completely removing power from the regulator. This also prevents letting additional smoke out if the regulator 'guts' are shorted to ground internally. ________________________________ Message 5 _____________________________________ Time: 06:58:20 AM PST US Subject: AeroElectric-List: Re: Interesting thread on overvoltage event From: "rv8ch" ceengland7(at)gmail.com wrote: > In the Z diagrams, follow all the wires leaving the regulator. One of them (the A terminal on the generic Ford model) goes through the alternator half of the master switch, to a 5A breaker, which is tied to the main buss. The 5A breaker supplies the regulator with its power. So with external regulators, you're removing the only source of electrons to the field by completely removing power from the regulator. This also prevents letting additional smoke out if the regulator 'guts' are shorted to ground internally. Duh - now I get it - the light has turned on! [Idea] Thanks! -------- Mickey Coggins http://www.rv8.ch/ Read this topic online here: http://forums.matronics.com/viewtopic.php?p=468806#468806 ________________________________ Message 6 _____________________________________ Time: 07:33:18 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Interesting thread on overvoltage event At 08:56 AM 4/26/2017, you wrote: > > >ceengland7(at)gmail.com wrote: > > In the Z diagrams, follow all the wires leaving the regulator. > One of them (the A terminal on the generic Ford model) goes through > the alternator half of the master switch, to a 5A breaker, which is > tied to the main buss. The 5A breaker supplies the regulator with > its power. So with external regulators, you're removing the only > source of electrons to the field by completely removing power from > the regulator. This also prevents letting additional smoke out if > the regulator 'guts' are shorted to ground internally. >Duh - now I get it - the light has turned on! [Idea] Thanks! What you have 'discovered' is the process by which an FMEA is accomplished. You study power, control, and potential fault paths for EVERY component in a system . . . to deduce: a. How can this part fail? b. If it fails, how will I know it? c. Can it fail in a 'hidden' condition . . . with a potential for misery in the cockpit? -or- d. is the failure pre-flight detectable? e. if it does fail, what are the consequences and what's the most elegant path to resolution? Unlike the reliability studies that endeavor to build confidence in numbers that may or may not have practical validity (who tests batches of components for a million hours?), the FMEA assumes that EVERY part WILL fail. Then the system integrator figures out how to mitigate that failure . . . i.e. PLAN-B. I've seen massive spread sheets that go into minute detail on every little component or feature in a system wherein the author proudly announces "Eureka! We have achieved MTBF Nirvana!" I find it takes a tiny fraction of the time and effort to conduct and resolve a simple FMEA that offers a demonstrable degree of probability for comfortable termination of flight. Congrats my friend with the hopes that this new insight will serve you well . . . Bob . . . ________________________________ Message 7 _____________________________________ Time: 07:40:48 AM PST US Subject: AeroElectric-List: Re: Is a battery contactor really needed? From: "eschlanser" It's been a couple of years since I designed my plane's electrical system with no battery contactor. What brand or style battery contactor is preferred/acceptable for a OBAM airplane with a Z - (x) wiring system? I installed the barrel style starter contactor but replaced it with the flat style when Bob recommended that change. Now I'm wondering if there's a new style of battery contactor that has superseded the barrel style. One advantage to eliminating the battery contactor is keeping the voltage available for starting that would be lost to the battery contactor. Eric - W10 with Z-8 inspired elec system.[/u] Read this topic online here: http://forums.matronics.com/viewtopic.php?p=468812#468812 ________________________________ Message 8 _____________________________________ Time: 01:32:13 PM PST US Subject: Re: AeroElectric-List: Re: Interesting thread on overvoltage event From: Jan de Jong Yes, thanks. Told myself something wrong once and believed it ever after. Jan de Jong On 4/15/2017 2:38 PM, MMiller wrote: > In a PM generator like the Rotax, frequency is > not a function of the number of coils in the stator, it's a function > of the number of magnets in the rotor divided by two. Divided by two > because the magnets are installed in the rotor with the poles > alternating. Just look at the flux lines of one circuit. Two magnets > in series inducing a field through the laminated stator of two coils. > The two coils are connected in series with one of the coils "crossed" > so the magnetic effect is additive. ________________________________ Message 9 _____________________________________ Time: 03:20:36 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Is a battery contactor really needed? At 09:39 AM 4/26/2017, you wrote: > >It's been a couple of years since I designed my plane's electrical >system with no battery contactor. > >What brand or style battery contactor is preferred/acceptable for a >OBAM airplane with a Z - (x) wiring system? I installed the barrel >style starter contactor but replaced it with the flat style when Bob >recommended that change. Now I'm wondering if there's a new style of >battery contactor that has superseded the barrel style. The 'whisky barrel' style contactors have a track record that goes back nearly 100 years. Process and materials improvements have been applied throughout that time . . . they are of excellent value. The recommended change for starter contactors was based on the fact that even low duty-cycle whisky-barrel devices featured large area, low pressure contact surfaces compared to the more modern devices designed specifically for starter control. But assuming you've got a Plan-B in place for managing a battery contactor failure (or its wiring, switch, terminals, etc) then the style is of little significance. If it were my airplane, the battery contactor would be one of these . . . http://tinyurl.com/koq788n . . . or its several cousins. Contactor failure in the whisky-barrel styles is rare and it usually announces an impending failure with finicky starter performance. So the first time you get an intermittent starter behavior accompanied by a black panel or 'chattering' starter contactor, then it's time to replace the critter (assuming your battery satisfactorily passes cap and load tests). >One advantage to eliminating the battery contactor is keeping the >voltage available for starting that would be lost to the battery contactor. energy demands of a battery contactor are trivial compared with that required to energize the starter . . . hence no energy conservation benefits there . . . Bob . . . ------------------------------------------------------------------------------------- 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.