Trouble shooting a three phase delta 240v bank. 1

[lines04]

On a three phase delta 240v bank consisting of 3 single phase transformers, I am getting a phase to phase voltage of 120v,120v,240v. The problem is a crossed primary supply with two phases at the same potential. Can anyone explain to me how this works. Thank you

 

[wareagle]

Phase A - B, Phase A - C and Phase B - C should read 240 volts. Depending how the phases are wires Phase A to gnd 120
Phase B to gnd 120 and Phase C to gnd 208 volts. Your reading indicate one of the phase fuses is blown.

 

[lines04]

If one of the primary fuses were blown on the high side of the transformer, you would get a 210v, 210v, 0v phase to phase. The delta bank im refering to is a three-wire secondary. The question im asking is why would you get 120v 120v, 240v on the secondary side if the red and white phase were at the same potential. (two primary wires wrapped downline)

 

[lines04]

This is a diagram of what i mean. When i was working in the field I seen this, I was just unsure on why the voltages were 120v, 120v, 240v.

 

[wareagle]

Check the attached dwg I retrieved from Wikipedia.If you have a blown fuse at P2, P1, P2 andP3 are now in series and
you have half voltage across P1-P2 and P2-P3. You have full
voltage across P1-P3.

 

[lines04]

What do you believe would happen in a three phase 240 delta bank if a two of the primary phases were at the same potential?

 

[lines04]

In my situation three single phase transformers are connected or bridged to get the voltages. The diagram you have provided me with is a Delta wye with the delta being the primary side. The situation im dealing with has a wye side and a delta secondary side

 

[lines04]

have you looked at my attachment