star-star transformar connections

[buzztester]

i am confused about star-star connections. i am studying for the masters exam and in the US the most popular is either delta-wye or delta-delta config...the test i have to pass uses these 4 questions:

*13. Connect the secondary of a 3-phase bank to give a 4-wire star
configuration

*17. Connect three single-phase transformers to form a delta-star
configuration

*18. Connect three single-phase transformers to form a star-delta 3-phase
bank

*19. Connect three single-phase transformers to form a star-star 3-phase
bank

* CLASS II ONLY

can someone give me a schematic or a website that gives this information?? i assume that star-star is the same as a wye-wye configuration, however i am not positive...thanks for the insight!!!

 

[davidbeach]

Star and wye refer to the same thing. Grounded wye - grounded wye is very common as a utility service transformer. The rest of the answers are part of your homework, any good electrical reference book should have plenty of information.

 

[waross]

Look for the RUS website. You can find the actual connections used in most of rural America. Pay particular attention to the wye delta or star delta connection and be prepared to support your answer. The connection shown in many older textbooks results in transformer failure.
try;

http://www.usda.gov/rus/electric/pubs/1728f-804.pdf

Note the caution on page 223.
yours