Matronics Email Lists Forum Index Matronics Email Lists
BBS Forum Interface to the Matronics Email Lists
 
 Get Email Distribution Too!Get Email Distribution Too!    FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

Is the OVP 5 A CB supposed to trip when I switch off the

 
Post new topic   Reply to topic    Matronics Email Lists Forum Index -> AeroElectric-List
View previous topic :: View next topic  
Author Message
nuckolls.bob(at)aeroelect
Guest





PostPosted: Mon May 28, 2018 9:09 am    Post subject: Is the OVP 5 A CB supposed to trip when I switch off the Reply with quote

Quote:
Quote:
If you want to protect the relay contacts from back EMF generated in an inductive LOAD put a diode across the LOAD or across the relay contacts. Either place will work.


Relay and switch contacts are almost never fitted
with prophylactics against wear-n-tear. When you
read design life specs for the various products
you virtually never see recommendations for adding
external devices intended to extend service life
of the contacts.

The reason being that any 'arc snubbing' device
must be tailored to the application . . . the
relay/switch manufacturer cannot anticipate hou
YOU will used the product . . . hence, they are
what they are and any failure to meed design
goals for service life generally involves a
feature in the application that is out in left
field . . . a once in a million encounter with
the immutable laws of physics.

Good case in point was the rash of relay failures
we experienced in the B400 that took a couple years
to track down . . . and the relay manufacturer's
had no clue . . . hence not helpful.

https://goo.gl/QcfSYo

I've designed perhaps 4-5 products wherein it
was useful to add arc suppression directly
to contacts. The most recent being an OV
relay addition to a specific airplane with a generator
where the arc suppression was 'tuned' to
generator field inductance.




But for the most part, relays as switches are
selected to task with no adjuncts intended to
enhance service life.

Diodes and other solid state devices generally
serve no useful purpose across the contacts
of a switch. The Ceaans/FAA got caught with their
pants down around their ankles on the Great
ACS-Gerdes, OFF-L-R-Both-Start Keyswitch fiasco
circa 1990.

I captured the corrected documents here

https://goo.gl/QV3gTF


The first issue of these documents placed the
diode across the starter control switch contacts
in the ACS keyswitch assembly . . . only to
discover that the diode had no benefit. The
physics is described in the second page of

https://goo.gl/WUS1Ya






Bob . . .


- 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
Back to top
Display posts from previous:   
Post new topic   Reply to topic    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


Powered by phpBB © 2001, 2005 phpBB Group