×
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

Safe-off board - Whats the purpose?

Safe-off board - Whats the purpose?

Safe-off board - Whats the purpose?

(OP)
When I use a contactor monitoring circuit, then I pretty much know when the drive (VFD or servo drives) is powered, right? Then why do we have to buy the additional safe-off board (especially to the Powerflex Allen-Bradley drives)? Whats the purpose? Is it to get an additional safety certificate level??

Sriram

RE: Safe-off board - Whats the purpose?

If you use the safe off board you dont have to use a contactor on the input of the vfd.  I am assuming your using the external contactor as estop.  The safe off board is used also as estop function for different category levels depending on how you wire it in the manual.

RE: Safe-off board - Whats the purpose?

(OP)
Thanks Controlsdude. The E-stop logic is in the Smartguard controller. When the RESET push button is pressed, then I trigger the external contactor relay and monitor the contact(NC). Then I trigger the "Safe-off enable" signal to drive the safe-off board. Then I trigger the "Drive enable" signal to enable the drive...

I find too much redundancy in this logic, but I guess you are right that this is a requirement for a higher safety category level.   

RE: Safe-off board - Whats the purpose?

Yes, I can confirm that you need a "hardware safe" and "program error immune" way of doing it. The Safe-Off board is that part of the solution. Usually can't do it in SW only.

Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

RE: Safe-off board - Whats the purpose?

(OP)
Thanks Gunnar

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