---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sat 12/20/14: 5 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:11 AM - Re: stacking ring terminals on terminal post (Robert L. Nuckolls, III) 2. 11:52 AM - How does the Ducatti rectifier/regulator work? (user9253) 3. 12:08 PM - Re: How does the Ducatti rectifier/regulator work? (Robert L. Nuckolls, III) 4. 02:21 PM - Re: How does the Ducatti rectifier/regulator work? (Robert L. Nuckolls, III) 5. 04:43 PM - Re: How does the Ducatti rectifier/regulator work? (C&K) ________________________________ Message 1 _____________________________________ Time: 06:11:03 AM PST US From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: stacking ring terminals on terminal post At 22:49 2014-12-18, you wrote: These discussions on how many connectors on a single bolt caused me to recall an accident that a good friend was in. It was a large 46,000 lb. Army Boeing CH-47 Chinook helicopter. The helicopter had 8 fuel boost pumps distributed in 6 tanks to pump the fuel up to the engine driven pumps. The helicopter was lost when both of the turbine engines flamed out due to fuel starvation (not fuel exhaustion). All of the 8 boost pumps had the ground wires connected to one bolt. The bolt did OK, but due to vibration, the sheet metal it was anchored in failed and the bolt broke free of the airframe mount and thus the ground was lost to all of the fuel pumps. Boeing learned from that and soon had 4 ground bolts with the wires distributed between them, and a connector bus between all 4 bolts. It was a single point failure that had been overlooked by the design engineers. History has shown us a few lessons where rather simple design features were overlooked by very talented designers. Bottom line, there is more to this question than just how many terminals may be connected to one bolt. I have seen several references to single point failures in these discussions. Food for thought. Jim . . . . This illustrates the value of the FMEA. Don't suppose or calculate anything . . . assume the worst down to the fundamentals . . . the simple ideas. All those books full of rules-of-thumb are the top-layer attempt to avoid unhappy circumstances that can arise from an inability to look down into the layers of potential failure. I don't recall ever reading some words on bonding and/or limits to terminals on studs suggesting, "Oh, by the way, make sure that the thing you're bolting to isn't going to break/burn off as a consequence of stresses not addressed by this rule." The universe runs on physics. A huge puzzle of patterns that under ideal conditions, fit together with permanence and functionality. Most cases of a puzzle piece jammed into a less-than-best-fit is of little or no consequence. But sometimes, a 'hit' on the extreme end of the bell curve can cause the assembled puzzle to fall apart . . . and it's always a surprise. The artful component of our science is to be curious, cognizant and competent observers of how the most rudimentary of puzzle pieces have been assembled in the past . . . as a study in both success and failure. It's this knowledge of lessons-learned that offer foundation for future successes and minimizing risks in new adventures. In this endeavor, you cannot have too many observers nor is any intellectual exploration without value. This is how the potential for unhappy surprises are first resolved intellectually sitting at our keyboards . . . thus minimizing the risk of surprise at 5,000 feet . . . or on short final to the rocks. See: http://tinyurl.com/mwjbzt3 Bob . . . ________________________________ Message 2 _____________________________________ Time: 11:52:53 AM PST US Subject: AeroElectric-List: How does the Ducatti rectifier/regulator work? From: "user9253" A fellow RV-12 builder asked me this: > From the the little that I have read concerning dynamos, they operate at full output all the time as they have no field current controlling them. > Does that mean that if one runs the strobes and landing light all the time, the Ducati reg/rectifier will have less heat to dissipate through the cooling fins, and perhaps stay cooler and last longer? I do not know the answer, thus am asking the experts on the AeroElectric List. How does the Rotax 912 rectifier/regulator work? Does it short out the dynamo output to control voltage? Or does it add a series resistance to drop the output voltage? Or what? Thanks, Joe -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=435942#435942 ________________________________ Message 3 _____________________________________ Time: 12:08:09 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: How does the Ducatti rectifier/regulator work? At 13:51 2014-12-20, you wrote: > >A fellow RV-12 builder asked me this: > > From the the little that I have read concerning dynamos, they > operate at full output all the time as they have no field current > controlling them. > > Does that mean that if one runs the strobes and landing light all > the time, the Ducati reg/rectifier will have less heat to dissipate > through the cooling fins, and perhaps stay cooler and last longer? > >I do not know the answer, thus am asking the experts on the >AeroElectric List. How does the Rotax 912 rectifier/regulator >work? Does it short out the dynamo output to control voltage? Or >does it add a series resistance to drop the output voltage? Or what? >Thanks, Joe > >-------- Back 'in the day' when pm alternators were first being added to small bikes, the electrical output on the order of 5 amps did not offer a very challenging energy management problem. Earliest regulators simply used an SCR triggered on each of the alternator's half-cycle to simply short the AC output when the waveform was 'high enough' . . . this crude regulation philosophy caused the alternator to operated in a max-power-output mode all the time . . . with excess power being dissipated in the alternator's windings and the SHUNT mode, rectifier/regulator's heat sink. As the alternators go bigger and consumer design goals for more sophisticated electrical systems grew, there was a pretty popular shift to SERIES mode regulation. The B&C R/R products have always used this philosophy. The Ducatti regulators favored by Rotax were of this general design as well . . . http://aeroelectric.com/Pictures/Regulators/Rotax-Ducati_Rectifier-Regulator.jpg There are more modern versions of this design that use MOSFET transistors in the power control loop . . . designs that dissipate much less power as heat. Bob . . . ________________________________ Message 4 _____________________________________ Time: 02:21:03 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: How does the Ducatti rectifier/regulator work? At 13:51 2014-12-20, you wrote: A fellow RV-12 builder asked me this: . . . From the the little that I have read concerning dynamos, they operate at full output all the time as they have no field current controlling them. True, FULL output voltage, but not necessarily full output POWER. It's the job of the rectifier regulator to tailor the wild-frequency, wild-voltage AC into some reasonably stable output at the desired voltage. Bob . . . ________________________________ Message 5 _____________________________________ Time: 04:43:55 PM PST US From: C&K Subject: Re: AeroElectric-List: How does the Ducatti rectifier/regulator work? Can we assume that 820E and 2E2 resistors in the schematic are 820 ohm and 2R2 (2.2) ohm resistors? Ken do not archive > http://aeroelectric.com/Pictures/Regulators/Rotax-Ducati_Rectifier-Regulator.jpg > > ------------------------------------------------------------------------------------- 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.