×
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

Generator Differential Relay 87 Setting

Generator Differential Relay 87 Setting

Generator Differential Relay 87 Setting

(OP)
I will appreciate any help in setting the ABB differential relay (87M). The following are the available information:

(1) There are 3 ABB 419M relays (Model 419M, IB 7.6.1.7-1). They are used for differential protection (87M) of a 2250KW, 0.8 PF, 4.16KV, standby diesel generator. The two sets of CTs have a 600/5 ratio.

(2) The instruction I downloaded from ABB Website gives me only limited application information. This relay has a non-linear percent differential characteristic with a operation pick-up current of 0.1 to 0.5 Amp. The instruction didn't give a good example on how this relay should be set.

(3) Generally, we try to set the diffential relay to the minimum setting. How do I make a calculation to determine the minimum in this case. Is 0.1 Amp setting the suitable setting?

Regards,

RE: Generator Differential Relay 87 Setting

There's a little information on a similar Basler relay at http://basler.com/downloads/genprotguidC.pdf .

I'd also suggest calling your ABB rep, they're usually pretty good with those kinds of questions, or at least know someone with the answers.

RE: Generator Differential Relay 87 Setting


Don't usually drop names but call Cliff Downs in ABB's Allentown PA operation.

And, if it's the same relay, don’t forget to install that weird little 3ø outboard reactor that is shipped with the relay, or false trips may drive you bananas.  

I apologize for stating the obvious, but especially for the low-end settings of the I-T-E 87M, insist that all six CTs are identical and field proven to have the very same kneepoint.
  

RE: Generator Differential Relay 87 Setting

(OP)
Thanks for the quick reply from (Peebee) and (Busbar). I will follow up with the ABB contact provided by Busbar on Monday. They are located back East and have already left for today. Hopefully, I will get some recommendation from them.

Finding the right person to talk to is a challenge. Most companies are spread too thin and we are losing the technical capability very fast.

Appriciate all your help!

Regards,

RE: Generator Differential Relay 87 Setting

"Most companies are spread too thin and we are losing the technical capability very fast."

You can say that again.

RE: Generator Differential Relay 87 Setting


always remember, the best way to protect a generator winding is by use of high impedance differential protection and not by biased differential, as the setting keeps on increasing with fault current.

cheers

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