×
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

Transformer phase shifts

Transformer phase shifts

Transformer phase shifts

(OP)
For delta-wye 161-13 kV transformer, I'm not seeing a 30 degree shift between primary and secondary currents. In fact the secondary currents are LEADING the primary by 120 degrees. This is being seen on a SEL 787 relay. At this point the transformer is lightly loaded. Is this correct?

RE: Transformer phase shifts

In the default ANSI world, no it is not correct. No idea where you are, no idea what your specific application is. Who knows?

RE: Transformer phase shifts

Your relay may be looking at phase to phase load current on the delta and phase to neutral load current on another phase of the wye.

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

RE: Transformer phase shifts

Your 787 may have replaced individual single phase relays. When applied to a delta-wye, the CT secondaries would need to be wired wye-delta to undo the phase shift and filter out the zero sequence current. If applied to the existing system without modifying the CT wiring, your 787 should see 0 degrees shift. The 120 degree shift indicates incorrect phase to relay input wiring. With some tweaking of the W1CT, W2CT, W1CTC and W2CTC settings, the relay may be able to compensate for the mis-wiring and still show zero operate current for load and through fault current.

RE: Transformer phase shifts

I believe the ACCSELerator SW contains a commissioning tool that will help you sort things out. It should be supplied with the relay, or can be downloaded from the website.

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