Delt Configuration

Do anyone  know how to solve for Line voltage in a delta configuration see attachment please

View attachment New Doc 2018-09-12 15.31.24.pdf

I'm assuming that sketch is supposed to be a center tap on the 480V delta leg?

It can be solved from the diagram using simple vectors. 

Van = 480V*Sin(60deg) = 415.7 V

or

Van = sqrt(480^2 - 240^2)= 415.7 V

easy.  480/2 * 1.73 = 415

kduff70 said:

Do anyone  know how to solve for Line voltage in a delta configuration see attachment please

View attachment 11896

Click to expand...

Hi @kduff70,

The trick is realizing that it is actually complex number (or vector) addition and not just adding magnitudes. The surprising thing when you do this is that the longest leg of the center tapped delta is not the connection with the greatest voltage magnitude. 

Here is a cheat sheet PDF of the center tapped delta directly from our online course from our chapter on Transformer Connections. It has the diagram, proper labeling, formulas, phasor diagram, and an example of a 240V/208V/120V center tapped delta.  Feel free to print it out and take it with you to the exam:

View attachment Center Tapped Delta - Electrical PE Review.pdf



It's a large PDF. When you open it don't forget to zoom in to see the details. 

Also, if you need help with the open delta connection which is even more confusing, here is a detailed free article that will be a HUGE help (you can also print this out and take it with you to the exam):

Electrical PE Review - Open Delta Transformer Connection

Hope this helps!

Note:  When I type "V^" I meant to show the ^ symbol on top.

If V^An = V^AB + V^Bn = V^AB + 1/2*V^BC

Then V^An = 480V<30 + 1/2*480<-90 = 415.7<0

Interesting how this can be solved multiple ways.

Btw Zach's course is fantastic.  Highly recommend!  A lot of free articles on his site too.

thank you very much this was an eye opener