Matronics Email Lists :: View topic - best contactor reliability -- mechanical, solid state, or ma

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

best contactor reliability -- mechanical, solid state, or ma

Matronics Email Lists Forum Index -> AeroElectric-List

View previous topic :: View next topic

Author Message

hdwysong(at)gmail.com
Guest

Posted: Fri Jul 13, 2007 12:37 am Post subject: best contactor reliability -- mechanical, solid state, or ma

I have a remotely operated application where the loss of the 

master battery contactor will result in the loss of 

data/money/time (... and dignity!).  My baseline design 

resembles a "Z" diagram (thanks Bob!) and I planned to use a 

mechanical, continuous duty contactor like the S-701 from 

B&C.  However, a buddy of mine recently experienced a 

contactor failure in flight and it caused me to experience a 

few "What If!?" nightmares.  I'm back to reconsidering my 

original decision...



I wish I could skip the contactor entirely, but the 

components hanging off the master bus aren't switched (no 

ON/OFF control) so I need a master contactor to switch power.



The options I toyed with initially were a mechanical can 

(S-701), a solid state relay (Crydom D06D series), or a "hot 

rod" manual switch.



I've had good personal experience with the cans (no failures 

yet in hundreds of hours of flying).  Sure, they get hot and 

use/waste a little power but they have a good heritage.  Had 

my buddy not experienced a failure, I probably wouldn't have 

worried at all.  Now, I can't avoid worrying.



I've had good experience with the Crydom SSRs, too, and have 

only seen one coaxed to failure by a well-intentioned 

technician (25 Adc through a 7 Adc device... poof!).  Low 

power consumption, rugged, compact, moderately priced.



I've quizzed folks here about using manual "hot rod" 

contactors and received some great feedback (e.g. - don't 

use the cheap ones!).  Seemed bulletproof at first, but 

recent posts suggested these things can/have/will fail, too. 

  Perhaps it's just a problem with the cheap ones?  Dunno.



So, I'm sitting at square one (again!) trying to determine 

which of these options is most likely to keep me out of hot 

water.  I realize there is no "100% reliable" solution, but 

I'm weighing my options to get the greatest number of 9's in 

the long run.



Any feedback/wisdom from you folks will be greatly appreciated.



D

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

khorton01(at)rogers.com
Guest

Posted: Fri Jul 13, 2007 1:35 am Post subject: best contactor reliability -- mechanical, solid state, or ma

On 13 Jul 2007, at 04:38, D Wysong wrote:



 	  Quote: 	
		   



 I have a remotely operated application where the loss of the master  

 battery contactor will result in the loss of data/money/time (...  

 and dignity!).  My baseline design resembles a "Z" diagram (thanks  

 Bob!) and I planned to use a mechanical, continuous duty contactor  

 like the S-701 from B&C.  However, a buddy of mine recently  

 experienced a contactor failure in flight and it caused me to  

 experience a few "What If!?" nightmares.  I'm back to reconsidering  

 my original decision...



 I wish I could skip the contactor entirely, but the components  

 hanging off the master bus aren't switched (no ON/OFF control) so I  

 need a master contactor to switch power.



 The options I toyed with initially were a mechanical can (S-701), a  

 solid state relay (Crydom D06D series), or a "hot rod" manual switch.



 I've had good personal experience with the cans (no failures yet in  

 hundreds of hours of flying).  Sure, they get hot and use/waste a  

 little power but they have a good heritage.  Had my buddy not  

 experienced a failure, I probably wouldn't have worried at all.   

 Now, I can't avoid worrying.



 I've had good experience with the Crydom SSRs, too, and have only  

 seen one coaxed to failure by a well-intentioned technician (25 Adc  

 through a 7 Adc device... poof!).  Low power consumption, rugged,  

 compact, moderately priced.



 I've quizzed folks here about using manual "hot rod" contactors and  

 received some great feedback (e.g. - don't use the cheap ones!).   

 Seemed bulletproof at first, but recent posts suggested these  

 things can/have/will fail, too.  Perhaps it's just a problem with  

 the cheap ones?  Dunno.



 So, I'm sitting at square one (again!) trying to determine which of  

 these options is most likely to keep me out of hot water.  I  

 realize there is no "100% reliable" solution, but I'm weighing my  

 options to get the greatest number of 9's in the long run.



 Any feedback/wisdom from you folks will be greatly appreciated.


	


I assume that this is not an aircraft we are talking about.



If you have an application where you must absolutely ensure  

continuity of power, then you have to assume that any single  

component could someday fail, no matter how good quality that  

component is.  How about two contactors in parallel, with some sort  

of periodic check to ensure that they are both working, or some way  

to monitor them to have evidence that they are both working?  For  

monitoring, you could have each contactor feeding through a diode,  

and monitor the voltage between the contactor and the diode.  If the  

contactor fails, that voltage will drop.  If the voltage shows that  

both contactors are closed, you could monitor that voltage to show  

that each contactor can be opened (one at a time, so you don't stop  

providing power to your application).



Kevin Horton         RV-8 (finishing kit)

Ottawa, Canada

http://www.kilohotel.com/rv8

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

Eric M. Jones

Joined: 10 Jan 2006
Posts: 565
Location: Massachusetts

Posted: Sat Jul 14, 2007 7:08 am Post subject: Re: best contactor reliability -- mechanical, solid state, o

Some reuse from an email to a customer here...)



Compare--- 

_____________________________Type 70__________GX-11

 

Weight.........................12.5 Oz.............18 Oz                    

Temp...........................50 DegC...........75-85 DegC             

    (50 degC 122 F) makes the type 70 unusable....

Position........................Cap Down..........Any

Environmental...............Dust-Proof.........Hermetically sealed

Coil Suppression............Must be added....Built in  

   B&C Type 70 uses diodes, GX-11 uses transorbs (SnapJacks!)

Continuous Amps............80 at 50C..........150A at 75C

Inrush A.........................150...................500-2000

Open against Vmax.......... 35V.................>>100V 

   (...same as Kilovac)                                   

Hold current.....................1.0 A................700 mA      

   (Kilovac is 100 mA, Gigavac has lower hold currents on request)

G-force opening...............2G ??................>>10G        



Anyway the GX11 will be about $120, but the Type 70 ($37.00 from Newark) is not really useable in my opinion. You may want the accessory contacts and long leads...couldn't hurt. 



The Kilovac EV200aaana (aka Blue Sea 9012) is still great (similar to the Gigavac GX11).



The type 70 is problematic even if very common and long in the tooth. It is deficient in four main areas:



1) Poor coil suppression (this can be retrofitted to improve it)

2) Inadequate operating temperature. My GUESS is that the early ones had fiber/bakelite interiors, now they are Nylon. Regardless 122F spec is way too low to use. 

3) Inadequate G force withstand. 2G ?? 

4) Open against Vmax. 35V. They could sustain an arc if the alternator runs away.



Pure solid state solutions are not quite ready. I have experimented with this, and continue to do so. There are some remarkable devices in development.



Mechanical contactors--"Flaming River" seems to come up when people talk about quality. I would like some people to describe what happens to lower quality mechanical contactors, but I haven't heard details.



"The despotism of custom is everywhere...the standing hindrance to human advancement." 

   --John Stuart Mill

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

_________________
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net

Eric M. Jones

Joined: 10 Jan 2006
Posts: 565
Location: Massachusetts

Posted: Mon Jul 16, 2007 2:38 pm Post subject: Re: best contactor reliability -- mechanical, solid state, o

I just ran across these. They should do. They are a little more expensive than the GX-11 or the Blue Sea 9012 (Kilovac EV200aaana). Frankly I can't see an advantage unless you find them on sale.



http://www.omron.com/ecb/products/pdf/en_g9ea_ec.pdf



Interesting note on coil suppressor from the Omron data sheet:



They caution that a varistor or a Zener plus diode should be used as a protective circuit for the coil. "Using a diode alone will reduce the switching characteristics." 



Never use diodes for this purpose on relays, especially contactors.



"What the West really has to offer is honesty. Somehow, in the midst of their horrid history, the best among the Gaijin learned a wonderful lesson. They learned to distrust themselves, to doubt even what they were taught to believe or what their egos make them yearn to see. To know that even truth must be scrutinized, it was a great discovery.... "

      -- David Brin, "Dr. Pak's Preschool"

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

_________________
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net

Display posts from previous:

	Matronics Email Lists Forum Index -> AeroElectric-List	All times are GMT - 8 Hours
Page 1 of 1

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum