×
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

Differential Realy operation

Differential Realy operation

Differential Realy operation

(OP)
One 63/31.5/31.5 MVA 220/7/7 Kv transformer star/star/star station start up transformer was charged from 220 Kv and kept under no-load for observation.After 28 hours transformer tripped on differential with HV lines showing 43 A in all phases (all currents in phase and not 120 out of phase) and neutral CT showing 134 A.ABB RET 670 .Current started rising in all phases 75 millisecond prior to faulttripping.Transformer,on testing,seems to be OK.Relay connections etc seems OK.

What can be the reason for such a tripping?

RE: Differential Realy operation

Hi PRC.
Ufff, Dificult say something w/o set-files and configuration and test report of stability.
First reason what I see.  Values what you wrote is signed on the (43x3=134A )  external earth fault and it closed via neutral of your transformer.That means, it show mistake in the setting, not taked in account I0 elimanation or Y/Yn group.
Best Regards.
Slava.
Level of current show --isn't internal fault.

RE: Differential Realy operation

prc, can you post the relay event files, preferably in COMTRADE format?

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