Ghost reading?

[drew33]

At work today i tested a 208v primary and 240v secondary transformer today. Replaced the breaker (40a double pole ite type BQ) to the primary side and observed on my secondary side my x1 reading was 120v and my x4 lead was 103v with no load. When a load was placed on the transformer my readings went to 141v(x1) and 90v(x4). This laod was for our hvac unit which has a smaller step down transformer from 240v to 24v which did receive 24v on its secondary side, however all the controls (thermostat, relays and contacter did not operate and on the heater control side of the unit i lost the 24v which is several feet away from the small 240v to 24v transformer. Repalced it and the same thing, checked wiring all good shape. I beleive i'am getting a ghost reading on my supply transformer the 208v to 240v on the secondary side, any thoughts?? Also the breaker would not reset why i replaced it.

 

[drew33]

Well today i disconnected the transformer , took it to the shop and connected it to our test station. Guess what almost the same voltages as above. I then connected a 240v motor to the secondary side and energized our test station and nothing. So i pretty much confirmed it had to of been ghosting my voltage readings. Ordered a new transformer today, it was pretty hard to find seeing how the system was designed 22 yrs ago. I do have a question? Would a 216v tap on a transformer be as capable as a transformer with a 208v tap on the primary side on a 208v single phase circuit? (208v primary 1ph 60 hz 10 kva 240v secondary) vs (216v primary 1ph 60hz 10 kva 240v secondary) I ordered the original 208v, but i was curious due to the cost diff. between the 2.