×
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

Fault current in YN/Yn0 transformer

Fault current in YN/Yn0 transformer

Fault current in YN/Yn0 transformer

(OP)
Could any please confirm or contradict my understanding regarding distribution of fault current between hv and lv winding of a YN (ungrounded)/YN(grounded) transformer for phase to ground fault on lv side.As permy understanding the fault current distribution on hv side will be 1:1:2 ratio for phase to ground to fault on lv side

RE: Fault current in YN/Yn0 transformer

(OP)
thanks for link to but it does not answer my question which is distribution of fault current on ungrounded star side for single line to ground fault on LV side which is grounded star.I have no doubt that fault current will flow on HV side but wasn't sure how will it spilt between the HV phases i.e will it be in the ration on 2:1:1 or just between two phases of HV side?

RE: Fault current in YN/Yn0 transformer

Your question is answered, along with quite a lot of explanation in the the previous thread that HamburgerHelper referenced. The theory of why is covered in the GE paper.

The short answer is: virtually no fault current will flow, unless the transformer is a three-limb core form type, in which case the phantom delta effect means that some current will flow. The fault current in the phantom delta case shouldn't be as much as it would be if you had a Grd-Y/Grd-Y or Delta/Grd-Y connection.

Cheers,
mgtrp

RE: Fault current in YN/Yn0 transformer

mgtrp is correct. When evaluating how fault current flows across the transformer windings, a couple of easy rules that can help:

There must be a complete path for the current to flow.

Ignoring exciting current, if current is flowing in a secondary winding there must be a corresponding (opposing) current flowing in the primary winding.

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