×
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

Pros & Cons of different trafo vector groups

Pros & Cons of different trafo vector groups

Pros & Cons of different trafo vector groups

(OP)
Hi everyone,
Could you please discuss the pros n cons and usage of different (most common) vector groups of distribution transformers including 2 wdg and three wdg e.g Dyn, Yyn, Ynynd, Ynynyn etc. Useful links are most welcome.
Thanks

RE: Pros & Cons of different trafo vector groups

Do you have an application in mind?
Some schemes work fine with single transformers and are problematic with some configurations of three phase transformers.
Look at some of the threads on resistance grounding to get some idea of the grounding considerations.
There may be a saving in insulation costs for a transformer intended to be connected only in grounded wye as opposed to a similar transformer suitable for delta connection. A delta primary will better distribute an uneven load on a generator or system. A delta secondary or tertiary winding has issues with primary phase loss and/or primary voltage unbalance.
Search this site for harmonic mitigation. You should find descriptions of complimentary phase shifting connections used in an office building to mitigate harmonic currents.
yours

RE: Pros & Cons of different trafo vector groups

(OP)
Thanks waross,
I am involved in HV substation design so mainly the transformers I am interested in are the ones distributing loads to secondary or tertiary S/S or transformers. We have all sorts of consumers like industrial, domestic and commercial being supplied from the same transformer. So I am not able to think of any particular application. What can be the importance of S/S type like radial, double end fed and ring main S/S etc?
Is there any consideration of voltage level (like Transmission/sub tranmission and distribution level)for the selection of vector groups?

SMA

RE: Pros & Cons of different trafo vector groups

There are several regular members on the site with more experience than I with substation design. I will butt out for awhile and see what the experts say.
respectfully

RE: Pros & Cons of different trafo vector groups

For a start check:
http://www.beckwithelectric.com/powerlines/powerlines-37.html for two-winding transformers.

I also recommend reading the J&P Transformer Book for aditional info.




Failure seldom stops us, it is the fear for failure that stops us - Jack Lemmon

Make the best use of Eng-Tips.com
Read the Site Policies at FAQ731-376

RE: Pros & Cons of different trafo vector groups

(OP)
Thanks RalphChristie,
It is indeed a helpful link.

SMA

RE: Pros & Cons of different trafo vector groups

Delta-Wye transformer connection is one of the most popular configurations in the power utility and industrial applications because this connection act as a natural isolation of the zero sequence component avoiding nuisance tripping of utility side for the  most common faults such as phase to ground fault.

From the cost point of view, delta or any ungrounded transformer connections require full winding BIL. Therefore, the cost of the unit is more expensive.

Likewise, impedance grounded transformer also require higher BIL than grounded units.

For additional information on transformer connections see the image and links below.


ADDITIONAL INFORMATION
http://cuky2000.250free.com/Zigzag_Data.gif
http://cuky2000.250free.com/Three_Winding_Transf.gif

RE: Pros & Cons of different trafo vector groups

(OP)
All I can say that is GREAT ...
Thanks

RE: Pros & Cons of different trafo vector groups

WRT the last block of Cuky2000's table:

Generation applications typically use a dYN1 configuration as the GSU transformer with the generator connected at the LV delta and a high resistance earthing scheme (or transformer earthing scheme) applied at the generator star point. This is largely to allow limitation of generator earth faults to a mere handful of amps and save the hugely expensive stator core from severe damage in the event of an earth fault.

----------------------------------
  I don't suffer from insanity. I enjoy it...

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