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EFIS brown out protection

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N509RV(at)eckenroth.com
Guest

Posted: Thu Mar 26, 2009 5:39 pm Post subject: 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

  [quote][b]

nuckolls.bob(at)aeroelect
Guest

Posted: Fri Mar 27, 2009 1:48 am Post subject: EFIS brown out protection

At 08:33 PM 3/26/2009, you wrote:

 	  Quote: 	
		  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-  )

        ----------------------------------------

rnewman(at)tcwtech.com
Guest

Posted: Fri Mar 27, 2009 2:40 am Post subject: 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.

  

  

  

 [quote]   ---

Gig Giacona

Joined: 10 Jan 2006
Posts: 1416
Location: El Dorado Arkansas USA

Posted: Fri Mar 27, 2009 8:33 am Post subject: Intelligent Power Stabilizer

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

  

 Thanks,

 Bob Newman

 TCW Technologies, LLC.

  

  

  

 ---

_________________
W.R. "Gig" Giacona
601XL Under Construction
See my progress at www.peoamerica.net/N601WR

nuckolls.bob(at)aeroelect
Guest

Posted: Fri Mar 27, 2009 9:18 am Post subject: EFIS brown out protection

At 11:34 AM 3/27/2009, you wrote:

 	  Quote: 	
		  



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-  )

        ----------------------------------------

rnewman(at)tcwtech.com
Guest

Posted: Fri Mar 27, 2009 9:24 am Post subject: 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





---

nuckolls.bob(at)aeroelect
Guest

Posted: Fri Mar 27, 2009 9:43 am Post subject: EFIS brown out protection

At 12:16 PM 3/27/2009, you wrote:

 	  Quote: 	
		  



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-  )

        ----------------------------------------

rnewman(at)tcwtech.com
Guest

Posted: Fri Mar 27, 2009 1:06 pm Post subject: 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





---

ceengland(at)bellsouth.ne
Guest

Posted: Fri Mar 27, 2009 1:08 pm Post subject: EFIS brown out protection

Robert L. Nuckolls, III wrote:

 	  Quote: 	
		   

 <nuckolls.bob(at)aeroelectric.com>



 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

rnewman(at)tcwtech.com
Guest

Posted: Fri Mar 27, 2009 1:58 pm Post subject: 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





---

nuckolls.bob(at)aeroelect
Guest

Posted: Sat Mar 28, 2009 1:04 pm Post subject: EFIS brown out protection

 	  Quote: 	
		  >   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.


	


     Duhhh . . . I knew that!



     Hmmm . . . putting that much hardware between a perfectly

     good battery (ies) to offset a one-time, 50 mS brownout

     that occurs before you leave that ground seems like

     killing ants with a sledge.



     The obvious, stone simple work-around for equipment

     not designed to live in the real world of aircraft

     is to not fire it up until after the the engine starts.

     The second best is to provide a non-cranking battery

     to support weak sisters until after engine start.



     If your design goals call for an architecture with

     dual batteries anyhow, it seems a simple matter to

     arrange things so only the main battery is used to

     crank the engine.



     Once the engine is running then all features of all

     appliances can be expected to perform as advertised

     without having to make "mental adjustments" as to

     the new meaning of any particular display. If

     weight, parts count and cost of ownership are

     weighty features of your design goals, minimizing

     the amount of stuff to be purchased, installed,

     maintained and carried around as part of your

     empty weight should be carefully considered

     for magnitude of added value.

        Bob . . .



        ----------------------------------------)

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

        ----------------------------------------

N509RV(at)eckenroth.com
Guest

Posted: Sat Mar 28, 2009 5:18 pm Post subject: EFIS brown out protection

Bob 



Thanks for the heads up concerning the solid state contactor.  It does indeed reverse feed when not activated.  Does a relay such as S 704-1 act more like a mechanical switch.  Would it be reasonable to activate this relay using the start switch.

 

Paul



On Fri, Mar 27, 2009 at 6:33 AM, Bob-tcw <rnewman(at)tcwtech.com (rnewman(at)tcwtech.com)> wrote:

[quote]        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.

  

  

  

 [quote]   ---

Bill Schlatterer

Joined: 09 Jan 2006
Posts: 195

Posted: Sat Mar 28, 2009 7:21 pm Post subject: EFIS brown out protection

Bob, just curious, easy to see how it might handle a surge  but how does it handle a voltage sag from a single battery during starting  ??

  

 Thanks Bill S



   From:  owner-aeroelectric-list-server(at)matronics.com  [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of  Bob-tcw

Sent: Friday, March 27, 2009 5:34 AM

To:  aeroelectric-list(at)matronics.com

Subject: Re: 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.

  

  

  

 [quote]   ---

rnewman(at)tcwtech.com
Guest

Posted: Sun Mar 29, 2009 5:00 am Post subject: EFIS brown out protection

Bill,    The IPS system is a true  DC:DC power converter that takes input power from the power bus, and if  necessary boosts the voltage back up to 12 volts on its output.   The  output of the IPS is used to run equipment that you want to remain up during  engine cranking.  For input bus voltages from 5- 12 volts, the IPS system  maintains a supply voltage to EFIS, GPS or engine monitors at 12  volts.        Unlike an auxilary  battery,  the 4 amp IPS weighs 8 oz., requires no extra steering diodes,  and is maintenance free.       Hope this  helps,    detailed drawings and specifications are available at  this direct link:   http://www.tcwtech.com/IPS-12v.htm

  

  

 Thanks,

 Bob Newman 

 TCW Technologies, LLC.

  

  

  

  

 [quote]   ---

mrspudandcompany(at)veriz
Guest

Posted: Sun Mar 29, 2009 5:20 am Post subject: EFIS brown out protection

Bob, just curious, easy to see how it might handle a surge but how does it handle a voltage sag from a single battery during starting ??  

   

Thanks Bill S  

   

   

                        My understanding of this device is that it will boost up the voltage and maintain 12V even if the battery voltage drops down to near 5 volts, thus there will be no sag on it’s output.  This is unlike the simple linear regulator which will only regulate a higher voltage down to, say 12 volts, and if its input goes below the 12 volt threshold, then the output will also drop down.  

   

Roger      

  

From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Bob-tcw

 Sent: Friday, March  27, 2009 5:34 AM

 To: aeroelectric-list(at)matronics.com

 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.  

    

   

  [quote] [b]

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Mar 29, 2009 6:35 am Post subject: EFIS brown out protection

At 08:11 PM 3/28/2009, you wrote:

 	  Quote: 	
		  Bob



Thanks for the heads up concerning the solid state contactor.  It 

does indeed reverse feed when not activated.  Does a relay such as S 

704-1 act more like a mechanical switch.  Would it be reasonable to 

activate this relay using the start switch.


	


   Sure. That's the design philosophy illustrated in

   Figure Z-10/8.  A small brownout support battery

   is paralleled to the battery bus through the contacts

   of an S704-1 relay (or any similar device). The

   relay is energized at the same time as the starter

   contactor insuring that the brownout support

   battery is not taxed during the first 50 milliseconds

   or so that the battery is spinning up the starter

   armature. See:



http://www.aeroelectric.com/Pictures/Curves/99_Saturn_SL1_2.gif



   Of course, the e-bus loads are carried for the

   duration of a cranking event (time the starter

   button is depressed). This is longer than the

   system is "vulnerable" to brown out. Once the

   starter armature accelerates and is drawing

   more normal currents, the battery voltage comes

   back up to levels that probably supports

   vulnerable equipment.



   I think if it were my airplane, I'd simply

   start the engine before expecting all the

   electro-whizzies to be ready for flight.

   All were talking about here is a tailoring

   of the pre-flight checklist. I'm not suggesting

   that sophisticated power conditioning devices

   will not function as advertised. But it

   seems an unnecessarily complex solution to

   a 100 millisecond "problem" that occurs once

   per flight cycle before you've even departed

   the tie-down location. Rearrange the sequence

   of events during preflight and the problem

   goes away.

        Bob . . .



        ----------------------------------------)

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

        ----------------------------------------

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Mar 29, 2009 7:01 am Post subject: EFIS brown out protection

At 10:16 PM 3/28/2009, you wrote:

  	  Quote: 	
		   Bob, just curious, easy to see how it might handle a surge but how does it handle a voltage sag from a single battery during starting ??

  

 Thanks Bill S

 	


   Not sure which Bob you're addressing . . .



   There is a relatively new class of circuits developed

   as high efficiency voltage regulators. Unlike their

   linear ancestors, these circuits not only produce

   conditioned output BELOW input voltage, they can

   also STEP UP a too low voltage. Pretty smart gizmos.

   Indeed, these circuits SHOULD have been part of the

   original design goals for those "weak sisters" we're

   struggling with now.



   The technology is quite common in the TC aircraft

   world where electro-whizzies are DESIGNED to function

   as advertised with any input voltage over a wide

   range . . . usually 9 to 32 volts.



   I find it difficult to be benevolent toward my

   contemporaries who bring products to the OBAM

   aircraft community that ignore decades of lessons-

   learned. We shouldn't be having this conversation

   here on the List.



   I have never produced a device that required an

   system integrator, installer or a pilot to take special

   notice of some insufficiency in performance. That's

   what DO-160/Mil-STD-704 is all about. The guys who

   play in the big sandbox have enjoyed the benefits

   of this thoughtful design process for decades.



   It's disappointing to see neat and useful

   products come to the marketplace, crafted with

   perhaps thousands of hours of electronics and 

   software development time crying out for perhaps

   an additional 50 hours development time devoted

   to power input conditioning.



   We have some choices.



   (1) Do their job for them and install external power

   conditioning while driving up complexity, cost,

   weight and adding single points of failure for multiple

   equipment items.



   (2) We can add minimalist brownout protection schemes

   like Z-10/8.



   (3) We can re-sequence preflight events to work around

   vulnerabilities.



   (4) Above all, we should put suppliers of performance

   deficient devices on notice that they've fallen short

   of the best-we-know-how-to-do . . . and we're NOT

   happy about it. 



 

 

        Bob . . .



        ----------------------------------------)

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

        ----------------------------------------



     [quote][b]

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