×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Non-breaking electrical contacts

Non-breaking electrical contacts

Non-breaking electrical contacts

(OP)
I'm designing a relay that needs contacts for reversing a motor.  The starting and stopping of the current is done via a triac so the relay contacts do not have to start or break current.  The current will range from 10 - 70 amps.  I'm thinking I can do with simple silver plated copper.  Any thoughts?

RE: Non-breaking electrical contacts

Designing a relay is a specialized job -- why don't you just buy one ?

What is the voltage you want to switch? AC or DC ?

<nbucska@pcperipherals.com>

RE: Non-breaking electrical contacts

(OP)
We're using a T90 series right now that works o.k. for most of our customers.  The problem I have with it is that the NC contact doesn't have quite enough force.  Bending the spring to increase the force fixes the problem but of course increases the voltage needed to close the NO contact.  I can't find anything else that will fit onto our board.  I was hoping to avoid buying large quantities of silver cad oxide over copper contacts because we won't use enough of them.

RE: Non-breaking electrical contacts

Or an H-bridge configuration of FET's?

RE: Non-breaking electrical contacts

(OP)
My enclosure is too small for off-board relays.  The H configuration is something I will look at for the next generation.  Right now I have to fix a problem using the existing aluminum housing (no surfaces to mount the FETs for heat sinking).  I have found a contact manufacturer that has given me a quote on contacts nearly identical to what we are using.  I've got the magnetic circuit designed and the springs figured out.  I think I have a fix.  Thanks for the advice.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources