---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Thu 05/22/08: 16 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 01:38 AM - Coil Suppression Techniques () 2. 03:48 AM - Re: Coil Suppression Techniques (jetboy) 3. 06:18 AM - Re: Coil Suppression Techniques (Robert L. Nuckolls, III) 4. 06:59 AM - coil supression (bob noffs) 5. 10:49 AM - Re: Re: Coil Suppression Techniques (With Corrected Link) (John Cleary) 6. 11:14 AM - Re: Coil Suppression Techniques (Eric M. Jones) 7. 12:06 PM - Re: Re: Coil Suppression Techniques (Bob White) 8. 12:42 PM - Re: Coil Suppression Techniques () 9. 12:54 PM - Re: Coil Suppression Techniques (Eric M. Jones) 10. 01:32 PM - Re: Re: Coil Suppression Techniques (Bob White) 11. 01:40 PM - Previous Master solonoid clicking (Bill Bradburry) 12. 03:08 PM - Re: Coil Suppression Techniques (John Cleary) 13. 04:22 PM - Coil Suppression Techniques. (Tony Gibson) 14. 07:24 PM - Re: Fuse and Breaker - one bus (Chris) 15. 07:29 PM - Re: Fuse and Breaker - one bus (Chris) 16. 08:36 PM - Re: Coil Suppression Techniques (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 01:38:19 AM PST US Subject: AeroElectric-List: Coil Suppression Techniques From: Eric This seems to be a well studied subject and after studying your results the method of parallelling a relay or contactor with an opposite direction diode seems to be the quick and dirty but still quite adequate method for the homebuilder. Now a very practical question: Is a 0.1 dollar 1N4001...4004 or similar diode strong enough to handle the collapsing energy of any relay or contactor used in a homebuilt ? best regards Max (just now wiring my 701 starter circuit) ________________________________ Message 2 _____________________________________ Time: 03:48:04 AM PST US Subject: AeroElectric-List: Re: Coil Suppression Techniques From: "jetboy" Max, 1N5404 thru -8 series should do well with much more margin. I fitted one to the master solenoid on a Cessna150 once because the A&P in their collective wisdom neglected that small part as depicted it the Cessna parts book when replacing the old solenoid and damaged my master switch. My CH701 has a diode installed as required by the ACS ignition/start switch instructions and I think this one may have come with the switch. Ralph -------- Ralph - CH701 / 2200a Read this topic online here: http://forums.matronics.com/viewtopic.php?p=184325#184325 ________________________________ Message 3 _____________________________________ Time: 06:18:15 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Coil Suppression Techniques At 11:27 AM 5/22/2008 +0300, you wrote: >Eric > >This seems to be a well studied subject and after studying your results >the method of parallelling a relay or contactor with an opposite direction >diode seems to be the quick and dirty but still quite adequate method for >the homebuilder. > >Now a very practical question: > >Is a 0.1 dollar 1N4001...4004 or similar diode strong enough to handle the >collapsing energy of any relay or contactor used in a homebuilt Yes. Electrically the 1A diode is fine for about everything on the airplane. Recall that in the realm of reactive devices that store energy, the discharge begins at the same magnitude as the charging source. If you charge a capacitor to 100 volts, you get a reaction that starts at 100v and goes down from there when you discharge it. If you charge and inductor up to 1A, then when you release it from the charging source, the delivered reaction starts a 1A and goes down from there. Diodes have a steady state capability which is exemplified in their ratings . . . I.e, the 1N4001 is a 1A device. However, they also have transient ratings at much higher currents. For example, consulting the 1N400x data sheet at: http://aeroelectric.com/Mfgr_Data/Semiconductors/1N4001.pdf we read about an 8.3 mS non repetitive peak forward surge current rating of 30A. By "non-repeating", they don't mean "one time ever" but "just don't do this often." So as a transient current clamp on a manually operated contactor found in our airplanes the 1N400x series devices are electrically fine. However, I have often suggested that the larger siblings to the 1N400x (1N540x) devices have some mechanical advantages. They're still small but MUCH more robust than the little fellers. I selected these parts as power steering and coil suppressors of choice for the line of contactors I used to sell (which B&C still does). See: http://www.aeroelectric.com/Pictures/Contactors/s701-1l.jpg http://www.aeroelectric.com/Pictures/Contactors/s701-2.jpg The red PIDG terminal gets a good connection on the larger wires for these devices and the wires are robust enough to support the diode body under vibration levels typical of installations for these contactors. Radio Shack offers both sizes of diode: http://aeroelectric.com/Pictures/Misc/RS_Diodes.jpg Since a prohibition against Radio Shack parts has been suggested, I'll share an observation that there were times in the history of many suppliers of consumer/ experimenter parts where their offerings included industrial surplus parts of unknown but not necessarily evil pedigree. This includes a now premier supplier of goods (Digikey) who started out as a mail order supplier of industrial surplus that advertised in ham radio and experimenter electronics magazines. RS still handles experimenter's assortments of components that are reminiscent of "grab bags" offered in years gone by . . . http://tinyurl.com/5jhbu6 http://tinyurl.com/42jn9v . . . but these days, when you are responsible for managing inventory in thousands of stores, millions of catalogs, and a really big website, you don't spend time scrounging the back alleys of industrial trash cans looking for "floor sweepings". These components are so cheap that it simply doesn't pay to spend the time to salvage and then inventory less than factory-fresh components. The times they are a changing. As a final note, this thread is not intended to discourage anyone from using more sophisticated transient control techniques if that process rings their chimes. Information provided here is offered as a prophylactic against decision making based on poorly interpreted data, marketing hype, or sage advice from those who would disseminate but will not or cannot also teach. Bob . . . ________________________________ Message 4 _____________________________________ Time: 06:59:42 AM PST US From: "bob noffs" Subject: AeroElectric-List: coil supression i believe b and c supplies a diode when you order a solenoid. bob noffs ________________________________ Message 5 _____________________________________ Time: 10:49:53 AM PST US From: "John Cleary" Subject: RE: AeroElectric-List: Re: Coil Suppression Techniques (With Corrected Link) Great data Bob. Thanks, John -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L. Nuckolls, III Sent: Thursday, 22 May 2008 9:50 AM Subject: AeroElectric-List: Re: Coil Suppression Techniques (With Corrected Link) At 05:47 PM 5/21/2008 -0500, you wrote: At 07:42 AM 5/21/2008 -0700, you wrote: I have this weird Deja Vu feeling that we have covered this subject before. And I will save you the trouble Bob....I know you'll never agree, and you'll retort with a long quasi-techno piece and then stumble TO EXACTLY THE WRONG CONCLUSION. Coil suppression and relay contact arcing have been well studied: See: http://relays.tycoelectronics.com/appnotes/ Basically (ESPECIALLY with contactors) Do not use diodes for coil suppression unless you're hoping for greatly reduced relay/contactor life, so you can get stuck in a remote area and have an adventure. I know people like this but they usually don't build airplanes. Gotta'-Have-Drama-Dammit! You've cited that document before. And I've read it several times both before you cited it and after you cited it. Kindly point out to me where the authors offer DATA supporting an assertion that the plain vanilla diode coil suppression has a profound effect on relay life. They correctly asserted and I confirmed that diodes do indeed extend the time from switch opening until energized contacts begin to move. This is opening delay. They went on to extrapolate that opening delay translates directly into slower contact spreading velocity and extrapolated further that this translated to increased contact wear. I did the experiments and published the results that argue against their extrapolations. If you have some data to the contrary, please share it with us. Just because you've read some words under the letter head and over the signatures of persons in high places does not make their words golden unless they're supported by data from and understanding of repeatable experiments. Here's what sane people have figured out: . . . are you suggesting I am less than sane?? Mechanical relays and contactors depend upon magnetism generated by an electric current running through a wire coil. When the current stops, the magnetic field collapses. But the relay does not know the difference between a wire coil moving in a magnetic field (as in a generator) or a magnetic field moving in a wire coil (as in a collapsing magnetic field). Thus a large voltage1000V to 1500V typicallyis induced in the coil. This current goes the same direction the original current didso it slows the contact openingallowing arcing, chatter, bouncing, contact welding and even re-closure! Yikes! Go to your workbench, measure it, document it and share it with us. Show me where my data and interpretation of my data is wrong. The important feature of relay and contactor operation that you're overlooking is the extreme relationship between magnetic force and air-gap. Air is an exceedingly poor conductor of magnetic lines of force. So while a diode does indeed slow the rate of drop in coil current (hence increased delay) once the armature comes unstuck from its seated condition, the effect of increasing air-gap is many times more influential than rate of decay in coil current. Went back to the workbench to look at the S704-1 in more detail. Here's the test setup: http://aeroelectric.com/Pictures/Schematics/Relay_Test_Setup.pdf Relay response with no coil suppression looks like this: http://www.aeroelectric.com/Pictures/Curves/S704-1_Drop-Out_Delay_without_Diode.jpg where we see the high voltage spike on the coil trace and a 2.5 mS dropout delay. WITH a coil suppression diode, we get relay response like this: http://www.aeroelectric.com/Pictures/Curves/S704-1_Drop-Out_Delay_with_Diode.jpg Dropout Delay is increased to 12.5 mS or about 5x longer than with the diode. This was the feature pointed out in the article you cited . . . where the authors extrapolated this into a commensurate slowing in contact spreading velocity (longer fires). However, when we take the diode off and look at transition time . . . http://www.aeroelectric.com/Pictures/Curves/S704-1_D-E_Transition_NoSuppression.jpg From the time the contacts FIRST open until they first contact the opposite side is 0.6 mS. Let's put the diode back on and we get . . . http://www.aeroelectric.com/Pictures/Curves/S704-1_D-E_Transition_Diode_Suppression.jpg Hmmm . . . transition increases to 0.75 mS, about a 25% increase NOT A 500% INCREASE. Let's go back an look at the traces I took where we were observing the arc in a spreading set of contacts with no diode . . . http://www.aeroelectric.com/Pictures/Curves/704-1OpeningTimeNoDiode.gif Here I could see about 0.21 mS of "fire" as compared with . . . (Here's the right trace) http://www.aeroelectric.com/Pictures/Curves/704-1OpeningTimeWithDiode.gif about 0.23 mS arcing when the diode was in place. Hmmm, there was an increase but not a very big one. In both cases, observed arcing times were about 1/3 the total transition time. Now let us consider another feature of relays and contactors that REALLY drives service life issues. Take a look at: http://www.aeroelectric.com/Pictures/Curves/S704-1_Contact_Bounce_with_Diode.jpg Where we see that after the first time the contacts touch, really get with the high-tempo hat-dance for perhaps several dozen closure and re-opening events. This means that for every operation of the switch on the panel, the contacts are getting 5-25 times more activity than the single switching event might suggest. Now look at: http://www.aeroelectric.com/Pictures/Curves/S704-1_Contact_Bounce_without_Diode.jpg Well fooey . . . even with the diode off the contacts do the cat-on-a-hot-tin-roof routine. Let us further consider that when folks like those Tyco engineers evaluate service life, they're working in the laboratory test environment and evaluating products where service life is measured in the tens of thousands of operations . . . 50,000 typical. 250,000 is not unusual. Let us suppose that their paper was based on real statistical studies of dozens of relays with various coil suppression techniques and yes, there was an observable increase in mean operations between failures from 45,744 to 49,666 by "optimizing" the coil suppression. Hmmm . . . 10% . . . that IS significant to Tyco and probabably most of their customers. They didn't speak to this kind of study in the paper you cited and I'd like to believe they've done their homework. Let us assume their undocumented assertions WERE correct on the scale I suggested. How does this affect the OBAM aircraft builder who's switches, relays and contactors probably won't see 5,000 operations over the lifetime of the airplane? Further, environmental stresses will be root cause for most replacements of such devices in personally owned, non-revenue generating light aircraft, not electrical stresses. In any case, the 5x increase in drop-out delay DOES NOT extrapolate into a proportionate drop in contact life. The common palliative is a diode AND zener in series, or better yet, a bidirectional zener across the coil. They call these Transils, Surmetics, Transorbs, TranZorbs, TransGuards, Mosorbs; the list is endless. (Over-paid executives dream up these names.) They are generic P6KE18CA bidirectional zeners. Jeeeeeze........ Eric, Of all the contributors to this list I expect more of you. We had some substantive discussions on the inner technical workings of various products and ideas in Plymouth a couple of years ago. You struck me as one who appreciates understanding and having a handle on the simple-ideas that go into your recipes for success. Please don't wave anyone's documents in the air as justification for an extrapolation of my infirmities. Let's not make this about you or me. May I suggest we explore, understand and then explain the physics. Make my day. Show me were I'm wrong. Bob . . . -- incoming mail is certified Virus Free. Checked by AVG. Bob . . . ----------------------------------------) ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) ---------------------------------------- Checked by AVG. Checked by AVG. ________________________________ Message 6 _____________________________________ Time: 11:14:41 AM PST US Subject: AeroElectric-List: Re: Coil Suppression Techniques From: "Eric M. Jones" > Eric > This seems to be a well studied subject and after studying your results the method of parallelling a relay or contactor with an opposite direction diode seems to be the quick and dirty but still quite adequate method for the homebuilder. Now a very practical question: Is a 0.1 dollar 1N4001...4004 or similar diode strong enough to handle the collapsing energy of any relay or contactor used in a homebuilt ? > best regards > Max The coil's collapsing magnetic field when the contactor is de-energized induces a high current that travels in the same direction as the original holding current, but is of much greater magnitude. This is why the relay contacts chatter and arc on opening, can re-close (and even weld closed). This is bad for everything electrical, especially contacts. The bidirectional zeners are very cheap, and well worth it. The kit I sell will do your whole airplane, or go to Digikey if you want to save a few bucks and buy a dozen P6KE18CA. The question you imply, "Would it do for the homebuilder?"....My answer is NO, Bob's is YES. Take your pick. But Tyco, Potter and Brumfield, Kilovac, Gigavac, Zettler, Here's what Gigavac says: COIL SUPRESSION "....coil suppression techniques such as single diode, resistor capacitor combination, resistor, or varistor noticeably slow down the release time of the relay and can effect the life of the relay or the use of the relay in the application. In carry-only applications, the release time may not be important so these less expensive coil suppression techniques can be used. However, if the release/reset time is important, or if the contacts are to interrupt a load, do not use these techniques and use the recommended zener-zener or diode-zener combination." (underlining mine) Gigavac makes the GX-11 which is a great battery and starter contactor for your airplane, they also make really big high-current, high-voltage stuff. Diodes were 1960's technology. There's a better way now. -------- Eric M. Jones www.PerihelionDesign.com 113 Brentwood Drive Southbridge, MA 01550 (508) 764-2072 emjones@charter.net Read this topic online here: http://forums.matronics.com/viewtopic.php?p=184398#184398 ________________________________ Message 7 _____________________________________ Time: 12:06:37 PM PST US From: Bob White Subject: Re: AeroElectric-List: Re: Coil Suppression Techniques On Thu, 22 May 2008 11:11:37 -0700 "Eric M. Jones" wrote: > > The coil's collapsing magnetic field when the contactor is de-energized induces a high current that travels in the same direction as the original holding current, but is of much greater magnitude. This is why the relay contacts chatter and arc on opening, can re-close (and even weld closed). This is bad for everything electrical, especially contacts. > > The bidirectional zeners are very cheap, and well worth it. The kit I sell will do your whole airplane, or go to Digikey if you want to save a few bucks and buy a dozen P6KE18CA. > > The question you imply, "Would it do for the homebuilder?"....My answer is NO, Bob's is YES. Take your pick. > > But Tyco, Potter and Brumfield, Kilovac, Gigavac, Zettler, > > Here's what Gigavac says: COIL SUPRESSION > > "....coil suppression techniques such as single diode, resistor capacitor combination, resistor, or varistor noticeably slow down the release time of the relay and can effect the life of the relay or the use of the relay in the application. In carry-only applications, the release time may not be important so these less expensive coil suppression techniques can be used. However, if the release/reset time is important, or if the contacts are to interrupt a load, do not use these techniques and use the recommended zener-zener or diode-zener combination." (underlining mine) Gigavac makes the GX-11 which is a great battery and starter contactor for your airplane, they also make really big high-current, high-voltage stuff. > > Diodes were 1960's technology. There's a better way now. > > -------- > Eric M. Jones > www.PerihelionDesign.com > 113 Brentwood Drive > Southbridge, MA 01550 > (508) 764-2072 > emjones@charter.net > > I think we need to revisit the physics here. The collapsing field induces a high VOLTAGE which is the opposite polarity of the applied voltage. The faster the current decreases, the higher the voltage spike. The suppression diode gives the current a place to go allowing it to decay more slowly, producing a lower voltage, reducing the arcing on the switch controlling the relay. The current will never exceed the original current flowing in the coil. Use of the suppression diode delays opening the relay because the current continues to flow for a longer time. The important point is that the suppression diode protects the switch controlling the relay. The effects on the relay contact arcing are secondary. Bob W. -- N93BD - Rotary Powered BD-4 - http://www.bob-white.com 3.8 Hours Total Time and holding Cables for your rotary installation - http://roblinstores.com/cables/ ________________________________ Message 8 _____________________________________ Time: 12:42:16 PM PST US Subject: RE: AeroElectric-List: Coil Suppression Techniques From: Thanks Bob et al, This is all very academic and provides excellent reading. Unfortunately I won't soon be a fellow in the IEEE and I have an airplane to build. Given the list of manufacturer's provided is there one who makes a quality relay with built in zener or combo protection for which I won't need to break out the heath kit? I want to use the relay to load my essential bus (alternate feed) as in Z-19. My expect load will be 25 amps. This is in keeping with the max load for the heat sink'd diode coming from the main bus. Glenn -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L. Nuckolls, III Sent: Thursday, May 22, 2008 9:13 AM Subject: Re: AeroElectric-List: Coil Suppression Techniques --> At 11:27 AM 5/22/2008 +0300, you wrote: >Eric > >This seems to be a well studied subject and after studying your results >the method of parallelling a relay or contactor with an opposite >direction diode seems to be the quick and dirty but still quite >adequate method for the homebuilder. > >Now a very practical question: > >Is a 0.1 dollar 1N4001...4004 or similar diode strong enough to handle >the >collapsing energy of any relay or contactor used in a homebuilt Yes. Electrically the 1A diode is fine for about everything on the airplane. Recall that in the realm of reactive devices that store energy, the discharge begins at the same magnitude as the charging source. If you charge a capacitor to 100 volts, you get a reaction that starts at 100v and goes down from there when you discharge it. If you charge and inductor up to 1A, then when you release it from the charging source, the delivered reaction starts a 1A and goes down from there. Diodes have a steady state capability which is exemplified in their ratings . . . I.e, the 1N4001 is a 1A device. However, they also have transient ratings at much higher currents. For example, consulting the 1N400x data sheet at: http://aeroelectric.com/Mfgr_Data/Semiconductors/1N4001.pdf we read about an 8.3 mS non repetitive peak forward surge current rating of 30A. By "non-repeating", they don't mean "one time ever" but "just don't do this often." So as a transient current clamp on a manually operated contactor found in our airplanes the 1N400x series devices are electrically fine. However, I have often suggested that the larger siblings to the 1N400x (1N540x) devices have some mechanical advantages. They're still small but MUCH more robust than the little fellers. I selected these parts as power steering and coil suppressors of choice for the line of contactors I used to sell (which B&C still does). See: http://www.aeroelectric.com/Pictures/Contactors/s701-1l.jpg http://www.aeroelectric.com/Pictures/Contactors/s701-2.jpg The red PIDG terminal gets a good connection on the larger wires for these devices and the wires are robust enough to support the diode body under vibration levels typical of installations for these contactors. Radio Shack offers both sizes of diode: http://aeroelectric.com/Pictures/Misc/RS_Diodes.jpg Since a prohibition against Radio Shack parts has been suggested, I'll share an observation that there were times in the history of many suppliers of consumer/ experimenter parts where their offerings included industrial surplus parts of unknown but not necessarily evil pedigree. This includes a now premier supplier of goods (Digikey) who started out as a mail order supplier of industrial surplus that advertised in ham radio and experimenter electronics magazines. RS still handles experimenter's assortments of components that are reminiscent of "grab bags" offered in years gone by . . . http://tinyurl.com/5jhbu6 http://tinyurl.com/42jn9v . . . but these days, when you are responsible for managing inventory in thousands of stores, millions of catalogs, and a really big website, you don't spend time scrounging the back alleys of industrial trash cans looking for "floor sweepings". These components are so cheap that it simply doesn't pay to spend the time to salvage and then inventory less than factory-fresh components. The times they are a changing. As a final note, this thread is not intended to discourage anyone from using more sophisticated transient control techniques if that process rings their chimes. Information provided here is offered as a prophylactic against decision making based on poorly interpreted data, marketing hype, or sage advice from those who would disseminate but will not or cannot also teach. Bob . . . ________________________________ Message 9 _____________________________________ Time: 12:54:56 PM PST US Subject: AeroElectric-List: Re: Coil Suppression Techniques From: "Eric M. Jones" > induces a high VOLTAGE which is the opposite polarity of the applied voltage. The faster the current decreases, the higher the voltage > spike. The suppression diode gives the current a place to go allowing > it to decay more slowly, producing a lower voltage, reducing the > arcing on the switch controlling the relay. The current will never > exceed the original current flowing in the coil. > > Use of the suppression diode delays opening the relay because the > current continues to flow for a longer time. The important point is > that the suppression diode protects the switch controlling the relay. > The effects on the relay contact arcing are secondary. Bob W. > -- > N93BD - Rotary Powered BD-4 - http://www.bob-white.com > 3.8 Hours Total Time and holding > Cables for your rotary installation - http://roblinstores.com/cables/ > If it were only so, what a nice world it would be! Please read: http://relays.tycoelectronics.com/appnotes/app_pdfs/13c3311.pdf -------- Eric M. Jones www.PerihelionDesign.com 113 Brentwood Drive Southbridge, MA 01550 (508) 764-2072 emjones@charter.net Read this topic online here: http://forums.matronics.com/viewtopic.php?p=184415#184415 ________________________________ Message 10 ____________________________________ Time: 01:32:29 PM PST US From: Bob White Subject: Re: AeroElectric-List: Re: Coil Suppression Techniques On Thu, 22 May 2008 12:51:56 -0700 "Eric M. Jones" wrote: > > > > induces a high VOLTAGE which is the opposite polarity of the applied voltage. The faster the current decreases, the higher the voltage > > spike. The suppression diode gives the current a place to go allowing > > it to decay more slowly, producing a lower voltage, reducing the > > arcing on the switch controlling the relay. The current will never > > exceed the original current flowing in the coil. > > > > Use of the suppression diode delays opening the relay because the > > current continues to flow for a longer time. The important point is > > that the suppression diode protects the switch controlling the relay. > > The effects on the relay contact arcing are secondary. Bob W. > > -- > > N93BD - Rotary Powered BD-4 - http://www.bob-white.com > > 3.8 Hours Total Time and holding > > Cables for your rotary installation - http://roblinstores.com/cables/ > > > > > If it were only so, what a nice world it would be! Please read: > > http://relays.tycoelectronics.com/appnotes/app_pdfs/13c3311.pdf > > -------- > Eric M. Jones > www.PerihelionDesign.com > 113 Brentwood Drive > Southbridge, MA 01550 > (508) 764-2072 > emjones@charter.net > OK, I've read it. What's your point? Quote: "When an electromechanical relay is de-energized rapidly by a mechanical switch or semiconductor, the collapsing magnetic field produces a substantial voltage transient in its effort to disperse the stored energy and oppose the sudden change of current flow." Note that this high voltage is not connected to the relay contacts and there is no mention of high currents being generated. It just doesn't happen. The high voltage is impressed across the switch controlling the relay. As Ralph (jetboy) recently posted, the A&P left off the diode resulting in the master switch being destroyed in his C150. All the problems with relay contact opening are associated with the slower opening time. Another quote: "The optimum switching life (for normally-open contacts) is therefore obtainew with a totally unsuppressed relay and statements of rated electrical life are usually based on this premise." In other words, for best contact life, don't use suppression. So why do we use it? To protect the controlling switch! Bob W. -- N93BD - Rotary Powered BD-4 - http://www.bob-white.com 3.8 Hours Total Time and holding Cables for your rotary installation - http://roblinstores.com/cables/ ________________________________ Message 11 ____________________________________ Time: 01:40:17 PM PST US From: "Bill Bradburry" Subject: AeroElectric-List: Previous Master solonoid clicking A while back, I discussed a clicking sound that I heard after I turned the alternator on when the engine was running. Today I discovered that my low voltage module was not working and when I removed it, the clicking went away. I tested the module by putting +9V on pin 4, grounded pin 5, and looked for the LED to come on and also for a ground to show up on pin 1. No light, no ground. Must have crapped out??!! I also noticed that when the module was disconnected, If I had the main battery set to "Alternator", and the engine battery set to "ON", I got about 13.4V. If I flipped the engine battery switch to "Auto", the voltage went up to about 14.6V. I was at a loss as to why this would be. I didn't try it with the engine battery set to "OFF", so I don't know what would have happened if I did. Does anyone have any ideas as to what was happening to cause the clicking if the module caused it, and why the voltage increase? I at first thought..I am turning one of the batteries off, so the voltage went up, but then I thought...why wouldn't the voltage regulator bring it back down in that case. Thanks for the help! Bill B ________________________________ Message 12 ____________________________________ Time: 03:08:34 PM PST US From: "John Cleary" Subject: RE: AeroElectric-List: Coil Suppression Techniques Bob, Reading all these comments, two questions come to mind. 1. Have you done the tests below with a zener-zener or a diode-zener combination to see how they compare with their IN 540x cousins? 2. Have you collected data on the effect on the switch controlling the relay to compare the four conditions:- No protection IN540x protection Zener-zerner protection Diode-zener protection? The data from question 1 will show us the effects on the relay under the various conditions being discussed. The data from Q2 will show us the effects on the switch controlling the relay under those same conditions. It seems both lots of data are required to determine the best way to protect the switch and at the same time protect the relay? - or am I missing something in this debate? Thanks once again, John -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L. Nuckolls, III Sent: Thursday, 22 May 2008 11:13 PM Subject: Re: AeroElectric-List: Coil Suppression Techniques At 11:27 AM 5/22/2008 +0300, you wrote: >Eric > >This seems to be a well studied subject and after studying your results >the method of parallelling a relay or contactor with an opposite direction >diode seems to be the quick and dirty but still quite adequate method for >the homebuilder. > >Now a very practical question: > >Is a 0.1 dollar 1N4001...4004 or similar diode strong enough to handle the >collapsing energy of any relay or contactor used in a homebuilt Yes. Electrically the 1A diode is fine for about everything on the airplane. Recall that in the realm of reactive devices that store energy, the discharge begins at the same magnitude as the charging source. If you charge a capacitor to 100 volts, you get a reaction that starts at 100v and goes down from there when you discharge it. If you charge and inductor up to 1A, then when you release it from the charging source, the delivered reaction starts a 1A and goes down from there. Diodes have a steady state capability which is exemplified in their ratings . . . I.e, the 1N4001 is a 1A device. However, they also have transient ratings at much higher currents. For example, consulting the 1N400x data sheet at: http://aeroelectric.com/Mfgr_Data/Semiconductors/1N4001.pdf we read about an 8.3 mS non repetitive peak forward surge current rating of 30A. By "non-repeating", they don't mean "one time ever" but "just don't do this often." So as a transient current clamp on a manually operated contactor found in our airplanes the 1N400x series devices are electrically fine. However, I have often suggested that the larger siblings to the 1N400x (1N540x) devices have some mechanical advantages. They're still small but MUCH more robust than the little fellers. I selected these parts as power steering and coil suppressors of choice for the line of contactors I used to sell (which B&C still does). See: http://www.aeroelectric.com/Pictures/Contactors/s701-1l.jpg http://www.aeroelectric.com/Pictures/Contactors/s701-2.jpg The red PIDG terminal gets a good connection on the larger wires for these devices and the wires are robust enough to support the diode body under vibration levels typical of installations for these contactors. Radio Shack offers both sizes of diode: http://aeroelectric.com/Pictures/Misc/RS_Diodes.jpg Since a prohibition against Radio Shack parts has been suggested, I'll share an observation that there were times in the history of many suppliers of consumer/ experimenter parts where their offerings included industrial surplus parts of unknown but not necessarily evil pedigree. This includes a now premier supplier of goods (Digikey) who started out as a mail order supplier of industrial surplus that advertised in ham radio and experimenter electronics magazines. RS still handles experimenter's assortments of components that are reminiscent of "grab bags" offered in years gone by . . . http://tinyurl.com/5jhbu6 http://tinyurl.com/42jn9v . . . but these days, when you are responsible for managing inventory in thousands of stores, millions of catalogs, and a really big website, you don't spend time scrounging the back alleys of industrial trash cans looking for "floor sweepings". These components are so cheap that it simply doesn't pay to spend the time to salvage and then inventory less than factory-fresh components. The times they are a changing. As a final note, this thread is not intended to discourage anyone from using more sophisticated transient control techniques if that process rings their chimes. Information provided here is offered as a prophylactic against decision making based on poorly interpreted data, marketing hype, or sage advice from those who would disseminate but will not or cannot also teach. Bob . . . Checked by AVG. 7:21 AM Checked by AVG. 7:06 AM ________________________________ Message 13 ____________________________________ Time: 04:22:45 PM PST US From: Tony Gibson Subject: AeroElectric-List: Coil Suppression Techniques. Hi Bob, on-behalf of myself and many others I'm sure I'd like to thank yo u for - first of all, your restraint, and of course-your informative post s that make it so easy for the rest of us to click-on the links of your -experiments.=0AI joined this list probably two years ago and a great dea l of what was discussed was over my head (and still is!) ... I received the daily emails and for the longest time would-check out the subject titles and more often than not delete the email.- Over time I've 'gotten up to speed', read your book, and spent the time to-learn-(whether the partic ular subject concerned my airplane or not).-=0AIt's all too easy to "gold plate the spec" to cover ALL conceivable conditions that a particular comp onent may see whether applicable or not.- It is of GREAT value to me that you repeatedly base your responses on OBAM-aircraft.- Meaning... if ag e/environmental factors, etc is going to kill my component before I or my d esigned system does then thats exactly what I need to know.--I have alw ays found your posts and advice to be practical in the real world (where mo st of us live with our little homebuilt airplanes)-and considerate of my time & money.=0AI continue to learn from all the contributors and contribut ions to the site.- Best Regards to all and my apologies for feeling the n eed to 'waste' bandwidth!- ;)=0ATony Gibson=0AWinnipeg, Manitoba-=0A=0A Time: 03:51:31 PM PST US=0AFrom: "Robert L. Nuckolls, III" =0ASubject: Re: AeroElectric-List: Coil Suppression Techniques.=0A=0A =0AAt 07:42 AM 5/21/2008 -0700, you wrote:=0A=0A>=0A>I have this weird Deja Vu feeling that we have covered this subject =0A>before. And I will save y ou the trouble Bob....I know you'll never agree, =0A>and you'll retort with a long quasi-techno piece and then stumble TO =0A>EXACTLY THE WRONG CONCLU SION.=0A>=0A>Coil suppression- and relay contact arcing have been well st udied: See:=0A=0A>http://relays.tycoelectronics.com/appnotes/=0A>=0A>Basica lly (ESPECIALLY with contactors) Do not use diodes for coil =0A>suppression unless you're hoping for greatly reduced relay/contactor life, =0A>so you can get stuck in a remote area and have an adventure. I know people =0A>lik e this but they usually don't build airplanes. Gotta'-Have-Drama-Dammit!=0A =0A- You've cited that document before. And I've=0A- read it several ti mes both before you cited it=0A- and after you cited it.=0A=0A- Kindly point out to me where the authors offer DATA=0A- supporting an assertion that the plain vanilla=0A- diode coil suppression has a profound effect o n relay life.=0A=0A- They correctly asserted and I confirmed that=0A- d iodes do indeed extend the time from switch=0A- opening until energized c ontacts begin to move.=0A- This is opening delay. They went on to extrapo late=0A- that opening delay translates directly into slower=0A- contact spreading velocity and extrapolated further=0A- that this translated to increased contact wear.=0A=0A- I did the experiments and published the re sults=0A- that argue against their extrapolations. If you=0A- have some data to the contrary, please share it=0A- with us.=0A=0A- Just because you've read some words under the=0A- letter head and over the signatures of persons=0A- in high places does not make their words golden=0A- unl ess they're supported by data from and=0A- understanding of repeatable ex periments.=0A=0A>Here's what sane people have figured out:=0A=0A- . . . - are you suggesting I am less than sane??=0A=0A>Mechanical relays and co ntactors depend upon magnetism generated by an =0A>electric current running through a wire coil. When the current stops, the =0A>magnetic field collap ses. But the relay does not know the difference =0A>between a wire coil mov ing in a magnetic field (as in a generator) or a =0A>magnetic field moving in a wire coil (as in a collapsing magnetic field). =0A>Thus a large voltag e1000V to 1500V typicallyis induced in the coil. =0A>This current goes the same direction the original current didso it =0A>slows the contact openinga llowing arcing, chatter, bouncing, contact =0A>welding and even re-closure! Yikes!=0A=0A- Go to your workbench, measure it, document=0A- it and sh are it with us. Show me where my=0A- data and interpretation of my data i s wrong.=0A=0A- The important feature of relay and contactor=0A- operat ion that you're overlooking is the extreme=0A- relationship between magne tic force and air-gap.=0A- Air is an exceedingly poor conductor of magnet ic=0A- lines of force. So while a diode does indeed slow=0A- the rate o f drop in coil current (hence increased=0A- delay) once the armature come s unstuck from its=0A- seated condition, the effect of increasing=0A- a ir-gap is many times more influential than rate=0A- of decay in coil curr ent.=0A=0A- Went back to the workbench to look at the S704-1 in=0A- mor e detail. Here's the test setup:=0A=0A=0Ahttp://aeroelectric.com/Pictures/S chematics/Relay_Test_Setup.pdf=0A=0A- Relay response with no coil suppres sion looks=0A- like this:=0A=0Ahttp://www.aeroelectric.com/Pictures/Curve s/S704-1_Drop-Out_Delay_without_Diode.jpg=0A=0A- where we see the high vo ltage spike on the coil=0A- trace and a 2.5 mS dropout delay.=0A=0A- WI TH a coil suppression diode, we get=0A- relay response like this:=0A=0Aht tp://www.aeroelectric.com/Pictures/Curves/S704-1_Drop-Out_Delay_with_Diode. jpg=0A=0A- Dropout Delay is increased to 12.5 mS or about 5x=0A- longer than with the diode. This was the feature=0A- pointed out in the article you cited . . . where=0A- the authors extrapolated this into a commensur ate=0A- slowing in contact spreading velocity (longer fires).=0A=0A- Ho wever, when we take the diode off and look at=0A- transition time . . . =0A=0Ahttp://www.aeroelectric.com/Pictures/Curves/S704-1_D-E_Transition_NoS uppression.jpg=0A=0A- From the time the contacts FIRST open until they=0A - first contact the opposite side is 0.6 mS. Let's=0A- put the diode ba ck on and we get . . .=0A=0Ahttp://www.aeroelectric.com/Pictures/Curves/S70 4-1_D-E_Transition_Diode_Suppression.jpg=0A=0A- Hmmm . . . transition inc reases to 0.75 mS, about=0A- a 25% increase NOT A 500% INCREASE.=0A=0A- Let's go back an look at the traces I took where=0A- we were observing t he arc in a spreading set of=0A- contacts with no diode . . .=0A=0Ahttp:/ /www.aeroelectric.com/Pictures/Curves/704-1OpeningTimeNoDiode.gif=0A=0A- Here I could see about 0.21 mS of "fire" as compared=0A- with . . .=0A=0A http://www.aeroelectric.com/Pictures/Curves/704-1OpeningTimeNoDiode.gif=0A =0A- about 0.23 mS arcing when the diode was in place. Hmmm,=0A- there was an increase but not a very big one. In both=0A- cases, observed arcin g times were about 1/3 the total=0A- transition time.=0A=0A- Now let us consider another feature of relays and contactors=0A- that REALLY drives service life issues. Take a look at:=0A=0Ahttp://www.aeroelectric.com/Pict ures/Curves/S704-1_Contact_Bounce_with_Diode.jpg=0A=0A- Where we see that after the first time the contacts=0A- touch, really get with the high-te mpo hat-dance=0A- for perhaps several dozen closure and re-opening=0A- events. This means that for every operation of the=0A- switch on the pane l, the contacts are getting=0A- 5-25 times more activity than the single switching=0A- event might suggest. Now look at:=0A=0Ahttp://www.aeroelect ric.com/Pictures/Curves/S704-1_Contact_Bounce_without_Diode.jpg=0A=0A- We ll fooey . . . even with the diode off the contacts=0A- do the cat-on-a-h ot-tin-roof routine.=0A=0A- Let us further consider that when folks like those Tyco=0A- engineers evaluate service life, they're working in=0A- the laboratory test environment and evaluating products=0A- where service life is measured in the tens of thousands=0A- of operations . . . 50,000 typical. 250,000 is not=0A- unusual. Let us suppose that their paper was based on=0A- real statistical studies of dozens of relays with=0A- var ious coil suppression techniques and yes, there=0A- was an observable inc rease in mean operations between=0A- failures from 45,744 to 49,666 by "o ptimizing" the=0A- coil suppression. Hmmm . . . 10% . . . that IS signifi cant=0A- to Tyco and probabably most of their customers.=0A- They didn' t speak to this kind of study in the paper=0A- you cited and I'd like to believe they've done their=0A- homework.=0A=0A- Let us assume their und ocumented assertions=0A- WERE correct on the scale I suggested. How does this=0A- affect the OBAM aircraft builder who's switches,=0A- relays an d contactors probably won't see 5,000=0A- operations over the lifetime of the airplane?=0A=0A- Further, environmental stresses will be root cause =0A- for most replacements of such devices in personally owned,=0A- non -revenue generating light aircraft, not electrical=0A- stresses. In any c ase, the 5x increase in drop-out delay=0A- DOES NOT extrapolate into a pr oportionate drop in contact=0A- life.=0A=0A=0A>The common palliative is a diode AND zener in series, or better yet, a =0A>bidirectional zener across the coil. They call these Transils, =0A>Surmetics, Transorbs, TranZorbs, T ransGuards, Mosorbs; the =0A>list is endless. (Over-paid executives dream u p these names.)- They are =0A>generic P6KE18CA bidirectional zeners.=0A> =0A>Jeeeeeze........=0A=0A- Eric,=0A=0A- Of all the contributors to thi s list I expect=0A- more of you. We had some substantive discussions=0A - on the inner technical workings of various products=0A- and ideas in Plymouth a couple of years ago. You=0A- struck me as one who appreciates understanding=0A- and having a handle on the simple-ideas that go=0A- i nto your recipes for success.=0A=0A- Please don't wave anyone's documents in the air as=0A- justification for an extrapolation of my infirmities. =0A- Let's not make this about you or me. May I suggest=0A- we explore, understand and then explain the=0A- physics. Make my day. Show me were I 'm wrong.=0A=0A- Bob . . .=0A=0A=0A ________________________________ Message 14 ____________________________________ Time: 07:24:18 PM PST US From: "Chris" Subject: Re: AeroElectric-List: Fuse and Breaker - one bus Thanks Bob. I see your point and will continue along those lines you describe. I have been thinking I may want to see an indication of a failure on certain items by seeing that breaker button pop out. Is that really something I need to see or know or do I use another indicator like a light? -Chris ----- Original Message ----- From: "Robert L. Nuckolls, III" Sent: Tuesday, May 20, 2008 11:33 PM Subject: Re: AeroElectric-List: Fuse and Breaker - one bus > > > At 09:16 AM 5/20/2008 -0400, you wrote: > >> >> >>I have been lurking here for a few years trying to absorb the power of >>aeroelectric but I am having trouble jumping from the schematics to the >>physical configuration. >>I am having trouble with the physical configuration of my RV-10 electrical >>system design. I am trying to draw up a Z-13 style system but I think I >>want my E-Bus to have a breaker for trim, flaps etc but the rest I want to >>use a fuse block. What would be a good way to combine the fuse and >>breaker block into one bus? Just run same gage wire to the e-bus primary >>and alternate feed to the fuse block and split off from block with same >>gage wire to the bar for the breakers? >>thanks in advance > > The e-bus is for things that you need during the en-route > mode of flight to maximize utilization of a limited resource. > If you're planning Z-13/8, then the e-bus can be easily > configured to handle an endurance load of 8 amps. > > The idea is that when the airport is in sight that you > can bring the main bus back on for using the battery to > run anything on the main bus using a battery that's held > completely in reserve for approach to landing. > > What's your rationale for breakers on these two systems? > Runaway disconnect? Breakers are exceedingly poor substitutes > for master disconnect systems . . . if indeed runaway is > a high order probability for creating a hazard. It's > probably easier to design a system that can't run away. > In other words, trim is an exceedingly low duty-cycle > load that runs happily from the e-bus . . . Flaps too > for that matter . . . but they aren't needed until approach > to landing and could stay on the main bus. I guess we > need to understand your concnerns. > > Bob . . . > > > ________________________________ Message 15 ____________________________________ Time: 07:29:30 PM PST US From: "Chris" Subject: Re: AeroElectric-List: Fuse and Breaker - one bus Vaughn, I had an MGB and am familiar with the Prince of Darkness. Your right I probably should not be doing wiring - to me this is the coolest part of the project when its done, but the worst to figure out and build. I am a mechanical guy through and through. -Chris ----- Original Message ----- From: "Gaye and Vaughn" Sent: Tuesday, May 20, 2008 10:48 PM Subject: Re: AeroElectric-List: Fuse and Breaker - one bus > > > The fuse block is your endurance bus. I would run a wire to the fuse block > post that would handle the combined loads on the fuse block and the load > on your breaker bar. I would then run a wire from the post on the fuse > block to the breaker bar that was large enough to handle the combined > loads of all the breakers. > > I once had an MGTF with Lucas electrics. Are you should be wiring? ;-) > > Vaughn Teegarden > Trying to figure it out myself...Don't listen to me. > > ----- Original Message ----- > From: "Chris" > To: > Sent: Tuesday, May 20, 2008 9:16 AM > Subject: AeroElectric-List: Fuse and Breaker - one bus > > >> >> >> I have been lurking here for a few years trying to absorb the power of >> aeroelectric but I am having trouble jumping from the schematics to the >> physical configuration. >> I am having trouble with the physical configuration of my RV-10 >> electrical system design. I am trying to draw up a Z-13 style system but >> I think I want my E-Bus to have a breaker for trim, flaps etc but the >> rest I want to use a fuse block. What would be a good way to combine the >> fuse and breaker block into one bus? Just run same gage wire to the e-bus >> primary and alternate feed to the fuse block and split off from block >> with same gage wire to the bar for the breakers? >> thanks in advance >> Chris Lucas >> RV-10 #40072 >> >> >> >> > > > ________________________________ Message 16 ____________________________________ Time: 08:36:49 PM PST US From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: Coil Suppression Techniques At 08:03 AM 5/23/2008 +1000, you wrote: > >Bob, > >Reading all these comments, two questions come to mind. > >1. Have you done the tests below with a zener-zener or a diode-zener >combination to see how they compare with their IN 540x cousins? Absolutely. The the worse case voltage spike occurs with zero suppression (where all energies are dissipated in the arcing across spreading switch contacts). The best scenario for arcing control is the plain vanilla diode where arcing is minimal because the negative going spike that would normally go -300 volts plus is clamped off at ground thus limiting the voltage stress across the switch contacts to 14 volts. >2. Have you collected data on the effect on the switch controlling the relay >to compare the four conditions:- > No protection > IN540x protection > Zener-zerner protection > Diode-zener protection? Sure. They all work within the limits of their physics. Even a plain resistor adds significant value for arc reduction . . . even if the least efficient of the lot. A capacitor/resistor combination works too. Recall the "condenser" across the points on an Kettering ignition system distributor? There's a LOT of ways each offering trade offs. But to date, I've discovered no simpler, easier to implement technique than use of the plain-vanilla diode. >The data from question 1 will show us the effects on the relay under the >various conditions being discussed. The data from Q2 will show us the >effects on the switch controlling the relay under those same conditions. It >seems both lots of data are required to determine the best way to protect >the switch and at the same time protect the relay? - or am I missing >something in this debate? I looked at all these variations and quite frankly they performed well. I thought I had the traces on my hard drive but I don't find them. If I get time tomorrow, I'll go plot them again. I've not included them in my offerings of data because they are all middle-ground for performance between NO suppression and the ULTIMATE suppression of a plain-vanilla diode. With one exception. At one time I personally embraced low voltage MOV's as viable contact preservation devices but discarded them after I went to the bench to check performance when a reader told me of his own experiments where visible arcing was not attenuated by any observable amount with MOVs. I was properly embarrassed and dutiful in correcting the gaff. It's one of those things that happens when understanding based on data sheets does not mesh with real world experiences. The debate here is not whether the alternative systems do their job. The debate is whether there is return on investment for acquiring "specialized" components sold not upon hard data and repeatable experiment. The only support is a kind of "new and improved" marketing hype based on poorly extrapolated conclusions in a "celebrity" document. In this case, engineers that published under the Tyco trade name. It appears Eric is unwilling to be a teacher based on his personal understanding of the physics supported by a willingness to explain it. I am saddened by this. I'll go get the data on the alternative techniques tomorrow. 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.