×
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

Common Emergency Stop

Common Emergency Stop

Common Emergency Stop

(OP)
I need an advise from forum members on the following:
I have 10 direct online drives utilizing smart motor protection relays and 3 ABB VSD drives that have an existing field local control station (start, stop, e-stop).  I need to upgrade this system and provide a centralized common e-stop (kill all emergency stop).  When activated this e-stop shall stop all of the 13 drives.
I like to find out how to implement this "kill all" e-stop so that it is legal and is inline with any standard you might know of.
Do I purchase an e-stop with multiple contacts and hard wire the contacts back to each individual drive circuit? Don't  know if I can find an e-stop with 13 contacts?
Do I puchase a simple e-stop and wire back to the PLC and let the PLC send a stop signal to each drive? Don't know if that's legal or is inline with any standards.  
Any advice on how best to do this is kindly welcomed.
 

RE: Common Emergency Stop

How about a pair of 8 pole relays as master control relays? One simple normally closed E-stop button to interrupt current to both relays.

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

RE: Common Emergency Stop

Over here in the UK the 'Pilz' brand of safety relays are an industry standard. They provide a number of positively-guided safety contacts, and expansion modules are available for applications requiring multiple contacts. There are other manufacturers too - Rockwell, for example.
  

----------------------------------
  
If we learn from our mistakes I'm getting a great education!
 

RE: Common Emergency Stop

Waross and Scotty have the bases covered. Master control relay if you want to stick with hard wired E-Stops and relays, or a Safety relay if you want to go the more fancy option.

Control relays are probably cheaper, if you want to go that way. If your application needs some sort of reporting of what E-Stop has been activated and where, then the Safety relay is probably the better option.

I wouldn't be using a normal PLC for any E-Stop functions.  

RE: Common Emergency Stop

Waross has a good (lps) answer. Use a single n/c switch to control the power to the coils of two (or more, as required) n/o relays. Then connect the n/o relay contacts in series with the individual drive e-stop circuits. The use of the n/c switch and the n/o relay(s) provides, in my opinion, fail-safe protection.

I would add that if one more more of these drives are installed on a single machine that there may already be a single e-stop circuit that controls multiple drives. If this is the case, you may not need 13 output contacts from your master e-stop switch/relay combination.  

However...My opinion does not necessarily meet the requirements for the electrical code in your region, the requirements for the type of industry you are in, or any specific requirements that your employer (or client) has.

You should be familiar with all of the above requirements when judging what design is best.  

RE: Common Emergency Stop

(OP)
Thank you all kindly for your helpfull feedback.  

 

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