×
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

Special Type Relay
2

Special Type Relay

Special Type Relay

(OP)
Hi All,
I am looking for a 12v dc relay that when powered with 12v dc (constant, not instant) will trigger the relay (ie close a circuit) but only for a preset period of time (eg 10 minutes).
In other words, although the 12v dc will power for a long period of time (let's say some hours), the relay will close the circuit only for 10 minutes and the re-open it again (although the 12v dc power will be still there...)

Hope I made it clear enough and best regards
Al

RE: Special Type Relay

Google for time delay relay or timer

RE: Special Type Relay

It can be done with any time delay relay that has both instantaneous and time delay contacts.   Just put the TDO contact in series with an NO instantaneous contact.  

Assuming I understood what was wanted....

RE: Special Type Relay

It appears so.  Remember that you will need a constant 12VDC (or other level) voltage source to maintain the timing function.

You might want to see if ABB has a multifunction relay equivalent to the A-B 700-FSM (click on the multifunction tab of the link that I gave above).  Multifunction relays are good if you think that there is a chance that the timing logic requirement will change.

RE: Special Type Relay

The relay that you have selected will fulfil the function that you have described to us.
However the final choice will depend on the application.
Depending on the application you may want to consider how you want the device to respond to a power failure.
And what action you want if the input signal is interrupted? Do you want the timing to stop or continue?
And again if the input is interrupted and re-established, do you want the timing to continue for the balance of the original  interval or do you want the timing to reset and start over?
Some times these points are not important. When they are important, choosing a device becomes a challenge.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Special Type Relay

And don't forget perhaps the most basic requirement of all, that the relay contact rating is sufficient for the load.  There was a discussion regarding this issue of DC contact ratings in the following thread: http://www.eng-tips.com/viewthread.cfm?qid=204694&page=8

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