---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Tue 05/20/08: 18 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 02:11 AM - Re: Re: S704-1 Relay Question (Andrew Butler) 2. 03:25 AM - Re: Any legacy regulator gurus out there? (jetboy) 3. 06:07 AM - battery tenders (bob noffs) 4. 06:35 AM - Re: Re: S704-1 Relay Question (Etienne Phillips) 5. 06:49 AM - Re: Contactor Locations (Robert L. Nuckolls, III) 6. 07:10 AM - Re: Re: S704-1 Relay Question (Robert L. Nuckolls, III) 7. 07:11 AM - Re: Re: Any legacy regulator gurus out there? (Robert L. Nuckolls, III) 8. 07:18 AM - Re: battery tenders (Robert L. Nuckolls, III) 9. 07:24 AM - Re: battery tenders (Robert L. Nuckolls, III) 10. 07:48 AM - Re: Re: S704-1 Relay Question (Andrew Butler) 11. 10:26 AM - Re: Re: S704-1 Relay Question () 12. 04:48 PM - Re: Contactor Locations (Les Kearney) 13. 05:40 PM - Re: Contactor Locations (Robert L. Nuckolls, III) 14. 05:40 PM - Re: Re: S704-1 Relay Question (Robert L. Nuckolls, III) 15. 06:19 PM - Fuse and Breaker - one bus (Chris) 16. 07:53 PM - Re: Fuse and Breaker - one bus (Gaye and Vaughn) 17. 08:20 PM - Re: Contactor Locations (Fiveonepw@aol.com) 18. 08:37 PM - Re: Fuse and Breaker - one bus (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 02:11:20 AM PST US From: "Andrew Butler" Subject: Re: AeroElectric-List: Re: S704-1 Relay Question Okay, I've read the Wikipedia and aeroelectric articles. So far so good. So, in the absence of the diode, where is the "arc" likely to occur? If I have understood correctly I'm saying at the E-BUS feed switch rather than at the switch in the relay. Am I correct? If not, why does the arc occur at the relay switch and not the feed switch. It has to do with the current flow path......... Thanks for your help. Andrew. ----- Original Message ----- From: "Etienne Phillips" To: aeroelectric-list@matronics.com Subject: Re: AeroElectric-List: Re: S704-1 Relay Question Date: Mon, 19 May 2008 17:40:15 +0200 It's called a fly-back diode. The coil of a relay is a fairly sizeable inductor, which means that a step-change in current is not really possible. What happens when the current to the coil is removed, the "inertia" of the inductor will force a current to continue flowing for a short while, generating large voltages and arcing across switch contacts. The fly-back diode gives this current a path to flow without interfering with the rest of the electrical system, and only comes into play when the coil is de-energized. For more info, go to http://en.wikipedia.org/wiki/Flyback_diode :-) Etienne 2008/5/19 Andrew Butler : Thanks Ron, though the diode I was referring is the 1N4001 across the coil of the S704 relay. There is something I don't know, cause I don't see it adding any functionality....... Andrew. ----- Original Message ----- From: "Ron Shannon" To: aeroelectric-list@matronics.com Subject: Re: AeroElectric-List: Re: S704-1 Relay Question Date: Mon, 19 May 2008 07:07:20 -0700 On Mon, May 19, 2008 at 6:11 AM, Andrew Butler wrote: Hello, At what level of load does an E-Bus become "heavy duty"? Also, what is the purpose of the diode? I know what a diode does, but what is its practical use in this instance? Cheers, Andrew. The level at which an E-bus becomes "heavy duty" is not a precise point, but certainly occurs when the E-bus is expected to carry loads that would strain or exceed limits for a standalone toggle switch. Although the S700 series switches are rated to 15A, you should probably be seriously considering a separate relay whenever load approaches 10A, IMHO. The diode keeps the E-bus from back feeding the Main bus when the E-bus alternate feed (direct from battery or battery bus) is ON. If the E-bus were allowed to back feed the Main bus, it would defeat the purpose of the E-bus, which is rapid, positive reduction of load upon alternator failure. Use of a diode instead of another switch eliminates the need to flip another switch (i.e., reduces chance for error, also, see "heavy duty" discussion above). Ron ist"> http://www.matronics.com/Navigator?AeroElectric-List ics.com . matronics.com/contribution =========== ======== === ________________________________ Message 2 _____________________________________ Time: 03:25:46 AM PST US Subject: AeroElectric-List: Re: Any legacy regulator gurus out there? From: "jetboy" Sir, I dont quite want to claim guru status, working on my previous C150A from '61 it was similar and I did reset the V reg to around 14.4 - it was sitting about 13 - and reset the I reg with a wirewound resistor (one of those old monster types with the sliding clamp) to get the output up to 12 amps or so from the 'as found' 6 amps. It was actually a 20 amp generator but 12 is enough when the professional fix would be 100s of miles and $ away I dont recall whether I altered the gaps or tension for this but I did it after cleaning the contacts from 40 years of pitting with a burnishing tool. Some time later I had a low charge again and discovered the aircraft master switch - which thoughtfully includes cutoff contacts for the generator field line - was in need of similar refurbishing. love these old systems because they are actually repairable - just go to where the smoke last escaped from... Moral of the story for me was I had wrongly assumed I knew enough not to check the aircraft schematics first. In all probability the regulator may have been OK but the worn switch in the field line had reduced the drive. It did no harm checking the regulator and it would have been a shame to have it binned as it looked like new inside just as the ones pictured. So I concur with your notion to have him only mess with the V reg - perhaps after cleaning the contacts and checking the other wiring for hidden resistance. Ralph -------- Ralph - CH701 / 2200a Read this topic online here: http://forums.matronics.com/viewtopic.php?p=183994#183994 ________________________________ Message 3 _____________________________________ Time: 06:07:39 AM PST US From: "bob noffs" Subject: AeroElectric-List: battery tenders earl, a few years ago when battery tenders was a topic here i got started on the h. f. units. i ran into a low voltagw problem. i remember a post back then about the adjustable pots. i opened one up and no adjustable pot. this was probably 2 years ago. that is why i shopped for them with my voltmeter. i dont believe h. f. management will let me take them in the backroom and test them anymore. bob noffs ________________________________ Message 4 _____________________________________ Time: 06:35:05 AM PST US From: "Etienne Phillips" Subject: Re: AeroElectric-List: Re: S704-1 Relay Question That is correct, in the E-bus Alternate Feed Switch in this case, or in a more general case when dealing with inductor-like components, it'll arc across whatever component tries to remove power to the relay. In the case of a solid-state IC, this will normally be the silicon wafer, which would let out the smoke and kill the chip. I know someone who lost a starter switch in his Cozy after about 15 engine starts because the fly-back diode was missing from the starter contactor, that's how marked the effect is... A new switch and one 50c fly-back diode later and no more problems. Hope that helps :-) Etienne 2008/5/20 Andrew Butler : > Okay, I've read the Wikipedia and aeroelectric articles. So far so good. > > So, in the absence of the diode, where is the "arc" likely to occur? If I > have understood correctly I'm saying at the E-BUS feed switch rather than at > the switch in the relay. Am I correct? > > If not, why does the arc occur at the relay switch and not the feed switch. > It has to do with the current flow path......... > > Thanks for your help. > > Andrew. > > ----- Original Message ----- > From: "Etienne Phillips" > To: aeroelectric-list@matronics.com > Subject: Re: AeroElectric-List: Re: S704-1 Relay Question > Date: Mon, 19 May 2008 17:40:15 +0200 > > It's called a fly-back diode. > > The coil of a relay is a fairly sizeable inductor, which means that a > step-change in current is not really possible. What happens when the current > to the coil is removed, the "inertia" of the inductor will force a current > to continue flowing for a short while, generating large voltages and arcing > across switch contacts. The fly-back diode gives this current a path to flow > without interfering with the rest of the electrical system, and only comes > into play when the coil is de-energized. > > For more info, go to http://en.wikipedia.org/wiki/Flyback_diode > > :-) > > Etienne > > 2008/5/19 Andrew Butler : > >> Thanks Ron, though the diode I was referring is the 1N4001 across the >> coil of the S704 relay. There is something I don't know, cause I don't see >> it adding any functionality....... >> >> Andrew. >> >> ----- Original Message ----- >> From: "Ron Shannon" >> To: aeroelectric-list@matronics.com >> Subject: Re: AeroElectric-List: Re: S704-1 Relay Question >> Date: Mon, 19 May 2008 07:07:20 -0700 >> >> On Mon, May 19, 2008 at 6:11 AM, Andrew Butler >> wrote: >> >>> Hello, >>> >>> At what level of load does an E-Bus become "heavy duty"? >>> >>> Also, what is the purpose of the diode? I know what a diode does, but >>> what is its practical use in this instance? >>> >>> Cheers, >>> >>> Andrew. >>> >> >> >> The level at which an E-bus becomes "heavy duty" is not a precise point, >> but certainly occurs when the E-bus is expected to carry loads that would >> strain or exceed limits for a standalone toggle switch. Although the S700 >> series switches are rated to 15A, you should probably be seriously >> considering a separate relay whenever load approaches 10A, IMHO. >> >> The diode keeps the E-bus from back feeding the Main bus when the E-bus >> alternate feed (direct from battery or battery bus) is ON. If the E-bus were >> allowed to back feed the Main bus, it would defeat the purpose of the E-bus, >> which is rapid, positive reduction of load upon alternator failure. Use of a >> diode instead of another switch eliminates the need to flip another switch >> (i.e., reduces chance for error, also, see "heavy duty" discussion above). >> >> Ron >> >> * >> >> ist">http://www.matronics.com/Navigator?AeroElectric-Listics.com >> .matronics.com/contribution >> * >> >> >> * >> >> * >> >> > * > > ist">http://www.matronics.com/Navigator?AeroElectric-Listics.com > .matronics.com/contribution > * > > > * > > > * > > ________________________________ Message 5 _____________________________________ Time: 06:49:32 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Contactor Locations At 09:03 PM 5/19/2008 -0600, you wrote: >Hi > > >I am trying to plan my RV10 electrical system and have a question for the >electrical mavens. That is, how far from avionics should battery >contactors be? I am looking at mounting my batteries in the sub panel area >and would like to co locate the contactors in the same area. Access is not >an issue but I am concerned about possible interference with the avionics. >I may end up locating the starter contactor on the same area as well. >Would this be a problem? > > >Cheers > > >Les Kearney Contactors are not high level antagonists to other components of the system. You mount contactors where it makes the most sense for their function. Battery contactors close to batteries, starter contactors close to starters, ect. In some architectures, they can be clustered together. In any case, there are no characteristics of a contactor that makes them a threat to anything other than the switch that controls them. See: http://www.aeroelectric.com/articles/spikecatcher.pdf http://www.aeroelectric.com/articles/spike.pdf Bob . . . ----------------------------------------) ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) ---------------------------------------- ________________________________ Message 6 _____________________________________ Time: 07:10:32 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: S704-1 Relay Question At 09:01 AM 5/20/2008 +0000, you wrote: >Okay, I've read the Wikipedia and aeroelectric articles. So far so good. > >So, in the absence of the diode, where is the "arc" likely to occur? If I >have understood correctly I'm saying at the E-BUS feed switch rather than >at the switch in the relay. Am I correct? > >If not, why does the arc occur at the relay switch and not the feed >switch. It has to do with the current flow path......... > >Thanks for your help. > >Andrew. Not sure what you're calling the "feed switch". With respect to contactors and relays, there is potential for effects of field collapse in an inductor to erode the contacts of the device that controls that contactor or relay. Hence, the long standing practice of adding spike suppression across the coils of such devices as illustrated in the Z-figures. Now, ANY time you break a circuit with the opening of hard contacts as in a switch, relay or contactor (that is carrying any amount of current at any voltage) there WILL be an arc formed in spreading gap between opening contacts. There was a school of thought circulated in the OBAM aircraft community a few years ago that for voltages and/or currents below some low level (I don't recall the numbers now) that no arcing would occur. So as an experiment, I took a miniature switch and sanded out the side of it like this: http://aeroelectric.com/Pictures/Switches/sm_switch_cutaway.jpg I fixtured it under the microscope and caused the NO contacts to carry 1 or 1/2 amp of current at 1.5 volts (alkaline d-cell). In a dark room I could clearly observe a tiny but bright blue arc in the spreading gap between the contacts when the circuit was broken. THIS ARCING IS NOT the phenomenon of concern with respect to noise or debilitating effects on controlling or controlled devices. Hence we rarely see arc suppression techniques applied to these effects. One exception is the quest for achieving the Beech Aircraft ov relay trip-life using relays some 30+ years ago as described in the chapter on OV Protection in the 'Connection. There is also a school of thought that suggests plain vanilla diodes across relay and contactor coils will cause a slowing of contact spreading velocity and is therefore an inducement to prolonged arcing at the opening contacts. Experiments on my bench showed that while adding a diode did indeed cause a DELAY IN OPENING of the contacts . . . http://www.aeroelectric.com/Pictures/Curves/704-1DelayNoDiode.gif http://www.aeroelectric.com/Pictures/Curves/704-1DelayWithDiode.gif . . . use of the plain vanilla diode produced no significant slowing of contact spreading velocity once they started to move. http://www.aeroelectric.com/Pictures/Curves/704-1OpeningTimeNoDiode.gif http://www.aeroelectric.com/Pictures/Curves/704-1OpeningTimeWithDiode.gif In any case, the arcing produced either at controlling switches -OR- contacts of the controlled devices IS NOT a widespread threat for damage to other components in the system. The strongest effect you'll experience from the behavior of an unsuppressed relay or contactor coil is a transient interference event. A few years ago I helped a builder track down why opening his avionics bus relay on an off-the-shelf integrated power distribution system caused his ov protection to trip. A diode across the relay coil fixed the problem. Bob . . . ________________________________ Message 7 _____________________________________ Time: 07:11:52 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Any legacy regulator gurus out there? At 03:21 AM 5/20/2008 -0700, you wrote: > >Sir, I dont quite want to claim guru status, working on my previous C150A >from '61 it was similar and I did reset the V reg to around 14.4 - it was >sitting about 13 - and reset the I reg with a wirewound resistor (one of >those old monster types with the sliding clamp) to get the output up to 12 >amps or so from the 'as found' 6 amps. It was actually a 20 amp generator >but 12 is enough when the professional fix would be 100s of miles and $ away > >I dont recall whether I altered the gaps or tension for this but I did it >after cleaning the contacts from 40 years of pitting with a burnishing tool. > >Some time later I had a low charge again and discovered the aircraft >master switch - which thoughtfully includes cutoff contacts for the >generator field line - was in need of similar refurbishing. love these old >systems because they are actually repairable - just go to where the smoke >last escaped from... > >Moral of the story for me was I had wrongly assumed I knew enough not to >check the aircraft schematics first. In all probability the regulator may >have been OK but the worn switch in the field line had reduced the drive. >It did no harm checking the regulator and it would have been a shame to >have it binned as it looked like new inside just as the ones pictured. So >I concur with your notion to have him only mess with the V reg - perhaps >after cleaning the contacts and checking the other wiring for hidden >resistance. > >Ralph Thank you for sharing this. I'll include it in my compilation of hands-on experiences to forward to the gentleman who also has an old C-150! Bob . . . ________________________________ Message 8 _____________________________________ Time: 07:18:59 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: battery tenders At 02:24 AM 5/20/2008 +0000, you wrote: > > >Hi db, >The older 42292 [or whatever (the previous generation)]did have a variable >resister on the circuit board. Nearly every one needed some adjustment as >I have a dozen or so. > >I purchased a minimum order of 100 ohm pots to install in the newer >units. I adjust them for 13.8 open circuit. > >I've repaired six or so [mine and others] as the common failure is the >transformer wire disconnects where it attaches to the plug that plugs into >the 110VAC. A sharp knife will separate the plastic housing around the >transformer providing access. I thought originally that trying to start >an engine with the unit connected would melt the solder at that joint but >I'm not sure. > >For the money they are hard to beat but as some say, you get what you pay >for.. >Earl Yup. The first "Battery Charger" I purchased from H.F. was this guy. http://aeroelectric.com/Pictures/Battery_Chargers/HF_Chargers/Junk_1.jpg It was simply a loosely regulated, low-level charger that might be classed as a "trickle-charger". No smarts at all meaning that its design did not attempt to produce a top-off charge followed by a non-charging support of terminal voltage for the purpose of offsetting internal leakage that would eventually discharge the battery. That device was evaluated years ago and it's a certainty that newer devices intended to compete in an increasingly sophisticated market will have improved features. The problem is a simple experiment to benchmark their performance for behavior and calibration which I will do as time permits. Bob . . . ________________________________ Message 9 _____________________________________ Time: 07:24:57 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: battery tenders At 02:24 AM 5/20/2008 +0000, you wrote: > > >Hi db, >The older 42292 [or whatever (the previous generation)]did have a variable >resister on the circuit board. Nearly every one needed some adjustment as >I have a dozen or so. > >I purchased a minimum order of 100 ohm pots to install in the newer >units. I adjust them for 13.8 open circuit. > >I've repaired six or so [mine and others] as the common failure is the >transformer wire disconnects where it attaches to the plug that plugs into >the 110VAC. A sharp knife will separate the plastic housing around the >transformer providing access. I thought originally that trying to start >an engine with the unit connected would melt the solder at that joint but >I'm not sure. > >For the money they are hard to beat but as some say, you get what you pay >for.. >Earl > > >-- skyking135 wrote: >< > >I have one of the 42292 units and measured the output voltage on my >particular unit to be around 12.7 volts, noload. It was only getting the >battery up to about 12.3 volts; not enough to keep a good charge on a >battery. So, being the curious one that I am, I popped open the cover to >see if I could figure out how to adjust the output voltage. I found a >spot on the circuit board for a varistor (VR1) that had a 55ohm resistor >soldered in that postion. I figured that must adjust the output voltage. >I simply replaced the 55ohm resistor with a 22ohm one I had on hand. >That boosted the ouptut to a more respectable 13.2 volts. It still will >only charge up to about 12.9 volts which is better than the 12.3 is was >reaching before. I think I will adjust the resistor again to see if I >can squeeze out a little more performance. > >Quality control is not high on the list of priorities with Harbor >Freight. You get what you pay for. The question that is more difficult to answer is how does this product behave when LOADED with a discharged battery. How much current does it put out, for how long and to what terminal voltage? Does it produce a recharge voltage curve that looks anything like this? http://www.aeroelectric.com/Pictures/Curves/schumacher_2.jpg The voltage you're measuring at very low output current (open circuit) may be spoofing the charger into believing that it's connected to a fully charged battery and causes it to drop into the MAINTENANCE mode where the 12.9 volt level you cited is quite acceptable. A smart-charger is a crafty little bugger that takes a bit more than a one-time voltmeter check to deduce its capabilities. Adjusting them for a MAINTENANCE level of 13.8 volts would be contrary to the design goals for a true battery maintainer. Bob . . . ________________________________ Message 10 ____________________________________ Time: 07:48:08 AM PST US From: "Andrew Butler" Subject: Re: AeroElectric-List: Re: S704-1 Relay Question All I ever wanted to know about that particular component on the Z-figures and then some. I very much appreciate this valuable resource (all things Aeroelectric) and your attention to detail Bob. I wired up my first harness last weekend and attached it to my TruTrak servo. I did so with a relative amount of confidence in what I was doing, how I was doing it, why I was doing it and how I would continue doing it for the rest of the electrical system. Fantastic! Without this resource, I can honestly say that I would have been groping in the dark ending up with a low quality piecemeal whole rather than a high quality coherent one. Very many thanks for this and for the answers to my future questions. Andrew. ----- Original Message ----- From: "Robert L. Nuckolls, III" To: aeroelectric-list@matronics.com Subject: Re: AeroElectric-List: Re: S704-1 Relay Question Date: Tue, 20 May 2008 09:06:38 -0500 At 09:01 AM 5/20/2008 +0000, you wrote: > Okay, I've read the Wikipedia and aeroelectric articles. So far so good. > > So, in the absence of the diode, where is the "arc" likely to occur? If I have understood > correctly I'm saying at the E-BUS feed switch rather than at the switch in the relay. Am I > correct? > > If not, why does the arc occur at the relay switch and not the feed switch. It has to do with > the current flow path......... > > Thanks for your help. > > Andrew. Not sure what you're calling the "feed switch". With respect to contactors and relays, there is potential for effects of field collapse in an inductor to erode the contacts of the device that controls that contactor or relay. Hence, the long standing practice of adding spike suppression across the coils of such devices as illustrated in the Z-figures. Now, ANY time you break a circuit with the opening of hard contacts as in a switch, relay or contactor (that is carrying any amount of current at any voltage) there WILL be an arc formed in spreading gap between opening contacts. There was a school of thought circulated in the OBAM aircraft community a few years ago that for voltages and/or currents below some low level (I don't recall the numbers now) that no arcing would occur. So as an experiment, I took a miniature switch and sanded out the side of it like this: http://aeroelectric.com/Pictures/Switches/sm_switch_cutaway.jpg I fixtured it under the microscope and caused the NO contacts to carry 1 or 1/2 amp of current at 1.5 volts (alkaline d-cell). In a dark room I could clearly observe a tiny but bright blue arc in the spreading gap between the contacts when the circuit was broken. THIS ARCING IS NOT the phenomenon of concern with respect to noise or debilitating effects on controlling or controlled devices. Hence we rarely see arc suppression techniques applied to these effects. One exception is the quest for achieving the Beech Aircraft ov relay trip-life using relays some 30+ years ago as described in the chapter on OV Protection in the 'Connection. There is also a school of thought that suggests plain vanilla diodes across relay and contactor coils will cause a slowing of contact spreading velocity and is therefore an inducement to prolonged arcing at the opening contacts. Experiments on my bench showed that while adding a diode did indeed cause a DELAY IN OPENING of the contacts . . . http://www.aeroelectric.com/Pictures/Curves/704-1DelayNoDiode.gif http://www.aeroelectric.com/Pictures/Curves/704-1DelayWithDiode.gif . . . use of the plain vanilla diode produced no significant slowing of contact spreading velocity once they started to move. http://www.aeroelectric.com/Pictures/Curves/704-1OpeningTimeNoDiode.gif http://www.aeroelectric.com/Pictures/Curves/704-1OpeningTimeWithDiode.gif In any case, the arcing produced either at controlling switches -OR- contacts of the controlled devices IS NOT a widespread threat for damage to other components in the system. The strongest effect you'll experience from the behavior of an unsuppressed relay or contactor coil is a transient interference event. A few years ago I helped a builder track down why opening his avionics bus relay on an off-the-shelf integrated power distribution system caused his ov protection to trip. A diode across the relay coil fixed the problem. Bob . . . =========== =========== =========== =========== ________________________________ Message 11 ____________________________________ Time: 10:26:50 AM PST US Subject: RE: AeroElectric-List: Re: S704-1 Relay Question From: Great thread... In our world it seems like we take relays for granted. They are amazing gadgets and I wanted to find more information on them. Below is a great link with detail on the very popular Bosch relay. It should be very clear as to their great benefit. There is no reason to stress a switch with a few of these in-line. http://www.bcae1.com/relays.htm#demo -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Andrew Butler Sent: Tuesday, May 20, 2008 10:45 AM To: aeroelectric-list@matronics.com Subject: Re: AeroElectric-List: Re: S704-1 Relay Question All I ever wanted to know about that particular component on the Z-figures and then some. I very much appreciate this valuable resource (all things Aeroelectric) and your attention to detail Bob. I wired up my first harness last weekend and attached it to my TruTrak servo. I did so with a relative amount of confidence in what I was doing, how I was doing it, why I was doing it and how I would continue doing it for the rest of the electrical system. Fantastic! Without this resource, I can honestly say that I would have been groping in the dark ending up with a low quality piecemeal whole rather than a high quality coherent one. Very many thanks for this and for the answers to my future questions. Andrew. ----- Original Message ----- From: "Robert L. Nuckolls, III" To: aeroelectric-list@matronics.com Subject: Re: AeroElectric-List: Re: S704-1 Relay Question Date: Tue, 20 May 2008 09:06:38 -0500 Nuckolls, III" At 09:01 AM 5/20/2008 +0000, you wrote: > Okay, I've read the Wikipedia and aeroelectric articles. So far so good. > > So, in the absence of the diode, where is the "arc" likely to occur? If I have understood > correctly I'm saying at the E-BUS feed switch rather than at the switch in the relay. Am I > correct? > > If not, why does the arc occur at the relay switch and not the feed switch. It has to do with > the current flow path......... > > Thanks for your help. > > Andrew. Not sure what you're calling the "feed switch". With respect to contactors and relays, there is potential for effects of field collapse in an inductor to erode the contacts of the device that controls that contactor or relay. Hence, the long standing practice of adding spike suppression across the coils of such devices as illustrated in the Z-figures. Now, ANY time you break a circuit with the opening of hard contacts as in a switch, relay or contactor (that is carrying any amount of current at any voltage) there WILL be an arc formed in spreading gap between opening contacts. There was a school of thought circulated in the OBAM aircraft community a few years ago that for voltages and/or currents below some low level (I don't recall the numbers now) that no arcing would occur. So as an experiment, I took a miniature switch and sanded out the side of it like this: http://aeroelectric.com/Pictures/Switches/sm_switch_cutaway.jpg I fixtured it under the microscope and caused the NO contacts to carry 1 or 1/2 amp of current at 1.5 volts (alkaline d-cell). In a dark room I could clearly observe a tiny but bright blue arc in the spreading gap between the contacts when the circuit was broken. THIS ARCING IS NOT the phenomenon of concern with respect to noise or debilitating effects on controlling or controlled devices. Hence we rarely see arc suppression techniques applied to these effects. One exception is the quest for achieving the Beech Aircraft ov relay trip-life using relays some 30+ years ago as described in the chapter on OV Protection in the 'Connection. There is also a school of thought that suggests plain vanilla diodes across relay and contactor coils will cause a slowing of contact spreading velocity and is therefore an inducement to prolonged arcing at the opening contacts. Experiments on my bench showed that while adding a diode did indeed cause a DELAY IN OPENING of the contacts . . . http://www.aeroelectric.com/Pictures/Curves/704-1DelayNoDiode.gif http://www.aeroelectric.com/Pictures/Curves/704-1DelayWithDiode.gif . . . use of the plain vanilla diode produced no significant slowing of contact spreading velocity once they started to move. http://www.aeroelectric.com/Pictures/Curves/704-1OpeningTimeNoDiode.gif http://www.aeroelectric.com/Pictures/Curves/704-1OpeningTimeWithDiode.gi f In any case, the arcing produced either at controlling switches -OR- contacts of the controlled devices IS NOT a widespread threat for damage to other components in the system. The strongest effect you'll experience from the behavior of an unsuppressed relay or contactor coil is a transient interference event. A few years ago I helped a builder track down why opening his avionics bus relay on an off-the-shelf integrated power distribution system caused his ov protection to trip. A diode across the relay coil fixed the problem. Bob . . . ========== ========== ========== ========== ________________________________ Message 12 ____________________________________ Time: 04:48:38 PM PST US From: Les Kearney Subject: RE: AeroElectric-List: Contactor Locations Bob Thanks for the help. I read in the Aeroelectric Guide that the contactor locations was not a big issue but wasn't sure how much flexibility I really had. A quick follow-up question: Will the electromagnets in the contactors be a problem for any avionics. My Magnometers will be in the tail so that is not a concern. Cheers Les -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L. Nuckolls, III Sent: May-20-08 7:45 AM Subject: Re: AeroElectric-List: Contactor Locations At 09:03 PM 5/19/2008 -0600, you wrote: >Hi > > >I am trying to plan my RV10 electrical system and have a question for the >electrical mavens. That is, how far from avionics should battery >contactors be? I am looking at mounting my batteries in the sub panel area >and would like to co locate the contactors in the same area. Access is not >an issue but I am concerned about possible interference with the avionics. >I may end up locating the starter contactor on the same area as well. >Would this be a problem? > > >Cheers > > >Les Kearney Contactors are not high level antagonists to other components of the system. You mount contactors where it makes the most sense for their function. Battery contactors close to batteries, starter contactors close to starters, ect. In some architectures, they can be clustered together. In any case, there are no characteristics of a contactor that makes them a threat to anything other than the switch that controls them. See: http://www.aeroelectric.com/articles/spikecatcher.pdf http://www.aeroelectric.com/articles/spike.pdf Bob . . . ----------------------------------------) ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) ---------------------------------------- ________________________________ Message 13 ____________________________________ Time: 05:40:31 PM PST US From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: Contactor Locations At 05:43 PM 5/20/2008 -0600, you wrote: > >Bob > >Thanks for the help. I read in the Aeroelectric Guide that the contactor >locations was not a big issue but wasn't sure how much flexibility I really >had. > >A quick follow-up question: Will the electromagnets in the contactors be a >problem for any avionics. My Magnometers will be in the tail so that is not >a concern. > Magnetometers ARE a potential victim of stray magnetic leakage from contactors but as a rule, if your magnetometer is at least 3' away from a potential antagonist, you're on solid ground. Another potential worry is stray field from the SD-20 alternator. We had problems with interference for a whisky compass mounted on the glare shield of the A36 . . . but the problem went away when the compass was moved upward about 10" onto the windshield. The effects of a potential antagonist on a magnetic navigation instrument is greatly attenuated by distance . . . a few more inches separation can make a lot of difference. On heavy iron birds, we usually mount magnetometers out in a wing just ahead of ailerons and use non-magnetic stainless fasteners in the immediate vicinity. Bob . . . ________________________________ Message 14 ____________________________________ Time: 05:40:31 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: S704-1 Relay Question At 02:45 PM 5/20/2008 +0000, you wrote: >All I ever wanted to know about that particular component on the Z-figures >and then some. > >I very much appreciate this valuable resource (all things Aeroelectric) >and your attention to detail Bob. I wired up my first harness last weekend >and attached it to my TruTrak servo. I did so with a relative amount of >confidence in what I was doing, how I was doing it, why I was doing it and >how I would continue doing it for the rest of the electrical system. Fantastic! > >Without this resource, I can honestly say that I would have been groping >in the dark ending up with a low quality piecemeal whole rather than a >high quality coherent one. > >Very many thanks for this and for the answers to my future questions. Andrew. You're most welcome my friend. I'm pleased that you've found the work so useful. Bob . . . ________________________________ Message 15 ____________________________________ Time: 06:19:02 PM PST US From: "Chris" 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: 07:53:15 PM PST US From: "Gaye and Vaughn" 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" 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 17 ____________________________________ Time: 08:20:09 PM PST US From: Fiveonepw@aol.com Subject: Re: AeroElectric-List: Contactor Locations In a message dated 05/20/2008 8:51:48 AM Central Daylight Time, nuckolls.bob@cox.net writes: In any case, there are no characteristics of a contactor that makes them a threat to anything other than the switch that controls them. >>> Be advised that mounting the master contactor next to your whiskey compass may result in undesired consequenses... 8-) Mark do not archive **************Wondering what's for Dinner Tonight? Get new twists on family favorites at AOL Food. (http://food.aol.com/dinner-tonight?NCID=aolfod00030000000001) ________________________________ Message 18 ____________________________________ Time: 08:37:16 PM PST US From: "Robert L. Nuckolls, III" 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 . . . ------------------------------------------------------------------------------------- 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.