×
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

Overcurrent Protection Coordination with Delta/wye Bank

Overcurrent Protection Coordination with Delta/wye Bank

Overcurrent Protection Coordination with Delta/wye Bank

(OP)
What is the best practice for sensing low side bus ground faults on a Delta-wye transformer with high side protection? Since a L-G fault on the low-side appears as a L-L fault on the high side, the phase overcurrent elements must react to this fault. If the transformer is on the larger side or has a high impedance, it becomes difficult to set the high side phase overcurrent elements at a level that allows for maximum transformer loading, but also still reacts to L-G faults on the low side of the transformer in a reasonable time span.

RE: Overcurrent Protection Coordination with Delta/wye Bank

SEL has a whitepaper on coordinating negative sequence overcurrent protection if you are interested in going that route.

RE: Overcurrent Protection Coordination with Delta/wye Bank

The best way would be to use a CT in the low side neutral for an overcurrent element.

RE: Overcurrent Protection Coordination with Delta/wye Bank

Depending on the system and economics, transformer differential protection is a good option. If your primary protection is fused, coordinate the fuse with the transformer damage curve. Most coordination software will give you two damage curves. The more sensitive one is for the situation you described.

"Throughout space there is energy. Is this energy static or kinetic! If static our hopes are in vain; if kinetic ù and this we know it is, for certain ù then it is a mere question of time when men will succeed in attaching their machinery to the very wheelwork of nature". û Nikola Tesla

RE: Overcurrent Protection Coordination with Delta/wye Bank

I agree with HamburgerHelper, perhaps, you can use the negative sequence overcurrent to the high transformer side protection. Check appendix II Faults on the secondary of a delta - wye transformer in paper "Negative-Sequence Overcurrent Element. Application and Coordination in Distribution Protection" link: https://www.google.com.pe/url?sa=t&rct=j&q...

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