---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Fri 03/27/09: 11 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 02:48 AM - Re: EFIS brown out protection (Robert L. Nuckolls, III) 2. 03:40 AM - Re: EFIS brown out protection (Bob-tcw) 3. 09:37 AM - Re: EFIS brown out protection (Gig Giacona) 4. 10:18 AM - Re: Re: EFIS brown out protection (Robert L. Nuckolls, III) 5. 10:24 AM - Re: Re: EFIS brown out protection (Bob-tcw) 6. 10:43 AM - Re: Re: EFIS brown out protection (Robert L. Nuckolls, III) 7. 10:58 AM - Re: Fusible Links and Bus Interconnects (tx_jayhawk) 8. 01:18 PM - Re: Re: Fusible Links and Bus Interconnects (Robert L. Nuckolls, III) 9. 02:06 PM - Re: Re: EFIS brown out protection (Bob-tcw) 10. 02:08 PM - Re: Re: EFIS brown out protection (Charlie England) 11. 02:58 PM - Re: Re: EFIS brown out protection (Bob-tcw) ________________________________ Message 1 _____________________________________ Time: 02:48:57 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: EFIS brown out protection At 08:33 PM 3/26/2009, you wrote: >Would an aux battery feed to the E Buss through a solid state >contactor keep the voltage from sagging if the contactor is >energized by the starter switch. The E Buss feed from the Main >Buss is through a diode. > >I will appreciate any facts and/ or opinions, I'm aware of no solid state relays that behave like a metallic switch. They work well to effect on/off control to a load that is never a power source . . . like landing lights, pitot heat, blowers, etc. However, solid state relays with the lowest ON resistance use power MOS-FET transistors. These critters come with a built in power diode across the transistor's control structure. This means that when the relay is OFF, power can back-feed from the "load" back toward the "source". What you've proposed may work as long as this potential for reverse current flow is an acceptable feature in your overall design goal. Figure Z-10/8 shows one way that a relay can be used to isolate an aux battery during engine cranking such that brownout transient does not propagate from main battery to the brown-out protection battery. http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/Z10-8A1.pdf Another scheme could simply treat the Aux Battery as a non-cranking device wired like Z-30 and supplying e-bus alternate power from the aux battery bus. http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/Z29K_30K.pdf In this case one simply closes the E-bus alternate feed switch and leaves the aux battery contactor open while cranking the engine. There are variations on the theme you can consider and it's not necessarily given that a solid state relay is unsuitable to the task. Just be aware of and account for its reverse power flow feature. Bob . . . ----------------------------------------) ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) ---------------------------------------- ________________________________ Message 2 _____________________________________ Time: 03:40:25 AM PST US From: "Bob-tcw" Subject: Re: AeroElectric-List: EFIS brown out protection Paul, One alternative to an auxiliary battery for voltage sag protection is a product we developed at TCW Technologies. Intelligent Power Stabilizer, IPS, provides regulated power to critical electronics with battery voltages ranging from 5-15 volts. This product was specifically developed to keep EFIS, GPS and engine monitors up and running during engine starting. It weighs less than 1 lb and requires no maintenance. All the details are avialable at www.tcwtech.com Thanks, Bob Newman TCW Technologies, LLC. ----- Original Message ----- From: Paul Eckenroth To: aeroelectric-list@matronics.com Sent: Thursday, March 26, 2009 9:33 PM Subject: AeroElectric-List: EFIS brown out protection Would an aux battery feed to the E Buss through a solid state contactor keep the voltage from sagging if the contactor is energized by the starter switch. The E Buss feed from the Main Buss is through a diode. I will appreciate any facts and/ or opinions, Paul Eckenroth N509RV ________________________________ Message 3 _____________________________________ Time: 09:37:55 AM PST US Subject: AeroElectric-List: Re: EFIS brown out protection From: "Gig Giacona" I have a question about this device. With the Dynon 180 and other EFIS/EMS systems the aircraft voltage is measured from the same wire that powers the unit. Doesn't this device defeat that ability to measure voltage? rnewman(at)tcwtech.com wrote: > Paul, One alternative to an auxiliary battery for voltage sag protection is a product we developed at TCW Technologies. Intelligent Power Stabilizer, IPS, provides regulated power to critical electronics with battery voltages ranging from 5-15 volts. This product was specifically developed to keep EFIS, GPS and engine monitors up and running during engine starting. It weighs less than 1 lb and requires no maintenance. All the details are avialable at www.tcwtech.com (http://www.tcwtech.com) > > Thanks, > Bob Newman > TCW Technologies, LLC. > > > > --- -------- W.R. "Gig" Giacona 601XL Under Construction See my progress at www.peoamerica.net/N601WR Read this topic online here: http://forums.matronics.com/viewtopic.php?p=236363#236363 ________________________________ Message 4 _____________________________________ Time: 10:18:33 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: EFIS brown out protection At 11:34 AM 3/27/2009, you wrote: > >I have a question about this device. With the Dynon 180 and other >EFIS/EMS systems the aircraft voltage is measured from the same wire >that powers the unit. Doesn't this device defeat that ability to >measure voltage? How so? ALL instruments display what they measure at the point of interest determined by design goals of the manufacturer. Bottom line is that watching the voltage or current at any point in the aircraft has some diagnostic but even less operational value. When it comes to a resurrection of some system in your airplane, probability of having EASY access to the most useful measurement points is close to zero. We've discussed the value of having alternator loadmeters versus battery ammeters. We've studied the value of knowing voltage on a host of "interesting" system nodes. Some years ago I proposed a non-digital implementation of the automotive diagnostics connector. See: http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/Electrical_System_Diagnostics.pdf That proposal brought 26 data points of interest to some handy location for the purposes of doing system failure diagnosis from the cockpit . . . with room to expand to 37 total. The odds of really NEEDING to look at any one of those points is tiny. But the FIRST time that access to a data point buried in the guts of your airplane saves you hours of trouble shooting time . . . the value of installing such features takes a quantum leap upward. I've been privileged to mitigate dozens of problems that had an airplane out of service for weeks if not months. My success had more to do with getting access to data than it was the deduction of what the data meant! The value of any single measurement is predicated on understanding its significance. The probability of any one measurement being significant in the constellation of potential troubleshooting tasks is small. Bob . . . ----------------------------------------) ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) ---------------------------------------- ________________________________ Message 5 _____________________________________ Time: 10:24:20 AM PST US From: "Bob-tcw" Subject: Re: AeroElectric-List: Re: EFIS brown out protection With equipment like the Dynon that only have a single power input, then the ability to measure voltages below 12 volts is lost. (voltages above 12 volts will read correctly) However, we have included a low voltage warning light with the IPS system. Below 12.0 volts the light will illuminate. Thanks, Bob Newman ----- Original Message ----- From: "Gig Giacona" Sent: Friday, March 27, 2009 12:34 PM Subject: AeroElectric-List: Re: EFIS brown out protection > > > I have a question about this device. With the Dynon 180 and other EFIS/EMS > systems the aircraft voltage is measured from the same wire that powers > the unit. Doesn't this device defeat that ability to measure voltage? > > > rnewman(at)tcwtech.com wrote: >> Paul, One alternative to an auxiliary battery for voltage sag >> protection is a product we developed at TCW Technologies. Intelligent >> Power Stabilizer, IPS, provides regulated power to critical electronics >> with battery voltages ranging from 5-15 volts. This product was >> specifically developed to keep EFIS, GPS and engine monitors up and >> running during engine starting. It weighs less than 1 lb and requires >> no maintenance. All the details are avialable at www.tcwtech.com >> (http://www.tcwtech.com) >> >> Thanks, >> Bob Newman >> TCW Technologies, LLC. >> >> >> >> --- > > > -------- > W.R. "Gig" Giacona > 601XL Under Construction > See my progress at www.peoamerica.net/N601WR > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=236363#236363 > > > ________________________________ Message 6 _____________________________________ Time: 10:43:22 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: EFIS brown out protection At 12:16 PM 3/27/2009, you wrote: > >With equipment like the Dynon that only have a single power input, >then the ability to measure voltages below 12 volts is lost. >(voltages above 12 volts will read correctly) However, we have >included a low voltage warning light with the IPS system. Below >12.0 volts the light will illuminate. Does the Dynon shut down its ability to display voltages below 12.0? What is the significance of knowing a transition across a 12.0 volt threshold? Bob . . . ----------------------------------------) ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) ---------------------------------------- ________________________________ Message 7 _____________________________________ Time: 10:58:15 AM PST US Subject: AeroElectric-List: Re: Fusible Links and Bus Interconnects From: "tx_jayhawk" Hi Bob, Thanks for the feedback...I re-reviewed 43.13 to try and better answer my own questions, but there was still a few things from your reply I was not clear on. > These notations suggest that connected devices should > be adjacent to each other. If you gotta go 10" for the > conductor, then so be it. But close proximity in > the airplane is a design goal. Is this just from a circuit protection standpoint (want it to be like "one" device)? 10" is ok...what about 2'? > Z-13/20 was eliminated from the z-figures. After > some considerable, afer-the-fact consideration I > decided I could claim to have been hung over when > I did it. It's just too clumsy. Z-12 or Z-14 are > better integrations of an SD-20 with a larger main > alternator. I'm now sure I understand why this is? My problem with Z12 is that both alternators are feeding the same point. If the connection from the main to ess bus fails, you've lost both alternators. It seems preferable to have the standby alt feed the e-bus more directly. Z14 has another battery, contactors, and other complexity I chose not to pursue. > Long lengths of wire (greater than 6" in the FAA > world) need some form of fault protection. Unless > your main bus is located within 6" of the breaker, > then protection is generally advised. Further, it > must be MUCH more robust than the 5A breaker which > is expected to operate FIRST during a crowbar ov event. > I would be interested in learning the origin of the 6" rule (I could not find in AC 43.13), but it still seems the wire already has circuit protection via the circuit breaker. I'm not sure I understand why two circuit protection devices are needed. There are obviously lots of power wires (for other loads) longer than 6" with only one source of circuit protection, so I am not sure why this is different? > They don't want > to be too short for thermal characteristics. 6" > is a good number used on many cars. But certainly > no longer. 6" is a max...2" is min? 3"? THanks, Scott Read this topic online here: http://forums.matronics.com/viewtopic.php?p=236393#236393 ________________________________ Message 8 _____________________________________ Time: 01:18:58 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Fusible Links and Bus Interconnects At 12:54 PM 3/27/2009, you wrote: > >Hi Bob, > >Thanks for the feedback...I re-reviewed 43.13 to try and better >answer my own questions, but there was still a few things from your >reply I was not clear on. > > > > These notations suggest that connected devices should > > be adjacent to each other. If you gotta go 10" for the > > conductor, then so be it. But close proximity in > > the airplane is a design goal. > >Is this just from a circuit protection standpoint (want it to be >like "one" device)? 10" is ok...what about 2'? You have to make the go/no-go decision as to how far you're willing to stretch contemporary conventions. The goal is to minimize risks to small gage feeders (by "small" we mean much smaller than the battery and cranking circuit wires). Occasionally we've needed to attach some device directly to the bus or other fat-wire feed power point in a TC aircraft where the amount of wire exposed to fault risk could be limited to 6" or so. Folks traditionally up-tight with the burning of ANY wire deduced that the hazards generated were small. Same philosophy was applied to fusible links in cars. Now, if you want to go for 12" or 10-feet, that's your decision and your responsibility for risk mitigation. Are you going to double insulate the wire? Extra special care to insure no damage that might create a fault? The choice is yours. I've recommended a fusible link as an upstream protection for the 5A crowbar OV shut down system. It's not a "rule" and would not perhaps even be mentioned in 43.13. My approach is to offer recipes for success based on my personal observations of history and experiences in analysis of failure mode effects. But the ultimate magnitude and nature of risk you're willing to assume is your choice. > > Z-13/20 was eliminated from the z-figures. After > > some considerable, afer-the-fact consideration I > > decided I could claim to have been hung over when > > I did it. It's just too clumsy. Z-12 or Z-14 are > > better integrations of an SD-20 with a larger main > > alternator. > >I'm now sure I understand why this is? My problem with Z12 is that >both alternators are feeding the same point. If the connection from >the main to ess bus fails, you've lost both alternators. It seems >preferable to have the standby alt feed the e-bus more >directly. Z14 has another battery, contactors, and other complexity >I chose not to pursue. How do you loose connection between the main bus and e-bus? Your presumption of risk is no different than loss of connection between the main bus and avionics bus in contemporary TC aircraft. The weakest link in the legacy main/avionics bus architectures is the avionics master switch. As described in detail on the website, the whole premise for installing such a switch has evaporated based on new design goals and product improvements over the past 40 years. Further, even thought I've eliminated the AV master from the Z-Figures, I've provided a second, reduced power consumption pathway in the form of an alternate feed directly from the battery. Z-12 offers two power paths to the e-bus re-enforced by two alternators driving a main bus with a reliability history approaching that of prop bolts. > > Long lengths of wire (greater than 6" in the FAA > > world) need some form of fault protection. Unless > > your main bus is located within 6" of the breaker, > > then protection is generally advised. Further, it > > must be MUCH more robust than the 5A breaker which > > is expected to operate FIRST during a crowbar ov event. > > > > >I would be interested in learning the origin of the 6" rule (I could >not find in AC 43.13), but it still seems the wire already has >circuit protection via the circuit breaker. One might accurately say it was pulled from a place were the sun don't shine. Consider the wire protected by the fusible link runs from bus to breaker, the breaker protects wire(s) downstream AND complies with design goals established by the crowbar ov protection philosophy were a BREAKER is used in an airplane otherwise protected by FUSES. If you have some OTHER ov protection scheme, perhaps the 5A breaker, extended bus wire AND fusible link is eliminated. In this case, field power comes directly from the fuse block on a 5 or 7A fuse. > I'm not sure I understand why two circuit protection devices are > needed. There are obviously lots of power wires (for other loads) > longer than 6" with only one source of circuit protection, so I am > not sure why this is different? A single protective device suffices when a circuit branch from the bus (or fat wires) is located where that power leaves the bus as in rows of breakers or fuses. Once I tie onto the fat wires for extening power from a fuse block to a panel mounted breaker, THAT small wire becomes vulnerable. In observance of the "rule of dark origins", the fusible link seems easy and reasonable. Likelihood that the fusible link will EVER be required to operate . . . exceedingly low. But then, 99.99% of all breakers and fuses installed in cars, airplanes, other vehicles and indeed your house run the lifetime of the system never being required to operate in defense of a fault condition. So, knowing that . . . how far are you willing to depart from legacy design goals? I cannot advise you there. My design goals go to the simplest, lowest cost, most robust implementation of proven recipes for success. Bob . . . ________________________________ Message 9 _____________________________________ Time: 02:06:01 PM PST US From: "Bob-tcw" Subject: Re: AeroElectric-List: Re: EFIS brown out protection The Dynon does not do anything strange with respect to reading bus voltage. Some devices, such as the Dynon Efis, have a single power input which is used to power the device as well as display the bus voltage. When they are powered through a TCW IPS product then they receive regulated 12 volt power regardless of the battery voltage. For bus voltages between 5-12 volts the output of the IPS product will regulate the voltage supplied to the load (EFIS), therefore, the EFIS will display a bus voltage of 12 volts. If the bus voltage rises above 12 volts the IPS will pass that voltage on to the load and therefore the bus voltage display on the EFIS will read correctly. To provide a pilot warning for low bus voltage the IPS system is supplied with a low voltage warning indicator to help annuciate a low voltage condition. Bob Newman TCW Technologies www.tcwtech.com ----- Original Message ----- From: "Robert L. Nuckolls, III" Sent: Friday, March 27, 2009 1:33 PM Subject: Re: AeroElectric-List: Re: EFIS brown out protection > > > At 12:16 PM 3/27/2009, you wrote: >> >>With equipment like the Dynon that only have a single power input, then >>the ability to measure voltages below 12 volts is lost. (voltages above 12 >>volts will read correctly) However, we have included a low voltage >>warning light with the IPS system. Below 12.0 volts the light will >>illuminate. > > Does the Dynon shut down its ability to display > voltages below 12.0? What is the significance of > knowing a transition across a 12.0 volt threshold? > > > Bob . . . > > ----------------------------------------) > ( . . . a long habit of not thinking ) > ( a thing wrong, gives it a superficial ) > ( appearance of being right . . . ) > ( ) > ( -Thomas Paine 1776- ) > ---------------------------------------- > > > ________________________________ Message 10 ____________________________________ Time: 02:08:21 PM PST US From: Charlie England Subject: Re: AeroElectric-List: Re: EFIS brown out protection Robert L. Nuckolls, III wrote: > > > At 12:16 PM 3/27/2009, you wrote: >> >> With equipment like the Dynon that only have a single power input, >> then the ability to measure voltages below 12 volts is lost. >> (voltages above 12 volts will read correctly) However, we have >> included a low voltage warning light with the IPS system. Below >> 12.0 volts the light will illuminate. > > Does the Dynon shut down its ability to display > voltages below 12.0? What is the significance of > knowing a transition across a 12.0 volt threshold? > > > Bob . . . I *think* that the original point was that with a 'switcher' feeding a regulated 13.8v to power the Dynon (being used as an engine/general electrical system health monitor), the Dynon wouldn't be able to tell the pilot that the bus voltage had begun to fall due to alternator or other failures in the electrical system, since there's no separate voltage monitor input on the Dynon. The 1st notice would be when the switcher drops off-line & everything goes dark. Charlie ________________________________ Message 11 ____________________________________ Time: 02:58:23 PM PST US From: "Bob-tcw" Subject: Re: AeroElectric-List: Re: EFIS brown out protection One other thing we did in the design of the IPS product was to set the regulated output voltage to just below 12 volts so that under normal conditions, i.e. alternator working properly, instruments like the Dynon will show a proper bus voltage of around 14 volts. When there is an alternator failure and the bus voltage starts to fall, there will be some indication on the instrument volt meter. (movement from 14 to 12.6). When you have an alternator failure the battery voltage rapidly falls from 14 volts down to about 12 to 12.6 where it sits whilst loads discharge the battery. Also, if you miss that clue and you miss the low voltage warning light illuminating at 12.0 volts, then somewhere around 8-9 volts of bus voltage a lot of other electronic devices in the plane will start to let you know that things have gone wrong. The good news is your EFIS will still be up :) -Bob Newman TCW Technologies ----- Original Message ----- From: "Charlie England" Sent: Friday, March 27, 2009 5:07 PM Subject: Re: AeroElectric-List: Re: EFIS brown out protection > > > Robert L. Nuckolls, III wrote: >> >> >> At 12:16 PM 3/27/2009, you wrote: >>> >>> With equipment like the Dynon that only have a single power input, then >>> the ability to measure voltages below 12 volts is lost. (voltages above >>> 12 volts will read correctly) However, we have included a low voltage >>> warning light with the IPS system. Below 12.0 volts the light will >>> illuminate. >> >> Does the Dynon shut down its ability to display >> voltages below 12.0? What is the significance of >> knowing a transition across a 12.0 volt threshold? >> >> >> Bob . . . > > I *think* that the original point was that with a 'switcher' feeding a > regulated 13.8v to power the Dynon (being used as an engine/general > electrical system health monitor), the Dynon wouldn't be able to tell the > pilot that the bus voltage had begun to fall due to alternator or other > failures in the electrical system, since there's no separate voltage > monitor input on the Dynon. The 1st notice would be when the switcher > drops off-line & everything goes dark. > > Charlie > > > ------------------------------------------------------------------------------------- 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.