delta to wye problem 1

[jeeprump]

hello connecting 112.5 kva transformer delta 480V primary and wye secondery 208V voltage between tubing (ground) and w is _135 V y is 237V and e is 330V .connecting 60kva transformer voltage is 0 V. How to explaine that? Can I connect X0 and ground to eliminate that "problem" thanks

 

[rbulsara]

Firstly, measure the voltages between X0 to each of the phases, if they all read 120V, then proceed to ground X0.

The X0 should always be grounded. Connected to the enclosure and also to building steel or other designated grounding electrode.

 

[jeeprump]

hi i forgot to correct on 60 kva trans. voltage between ground to each phases is 120 but using 112.5kva connected to the same line is 135V ,y is 237 and e is 330 v. why difference on these transformators? thank you

 

[rbulsara]

If the x0 is not grounded, you will measure 'abnormal' voltages to ground, as it has no real reference point and only capactive coupling to ground.

Ground x0 to the enclosure and also to the buildnig steel/grounding electrode.

Your 60kVA x0 may already be bonded to the enclosure.