4.16 kV/600 V transformer question

[rbyrne15]

I attended a job on Saturday where we maintained a delta/wye-connected transformer. The nameplate showed the normal tap voltage reference chart, with tap 2 shown to provide a line-line secondary voltage of 600 V, from a 4160 V input. Also shown on this chart was "% rated voltage" for each tap. Tap 2 (mentioned above), was shown as being 173% rated voltage.

I found this alarming, since I didn't think that a transformer winding could be subjected to such high voltages. I recognise that the 173% probably has something to do with the "root 3" relationship between phase and line voltages, but the rated voltage issue is confusing me.

Any help would be appreciated, thanks.

Richard Byrne.

 

[rbulsara]

This is my "guess".

If its referreing to Wye connected side, it would make some sense as the actual voltage "adjusted" in each winding (phase) will show as 173% change in Line to Line voltage.

Or the actual voltage adjusted per phase is 1/1.73 times the voltage change indicated on the nameplate.

 

[jghrist]

What are the "% rated voltages" for the other taps. Sounds like just a non-standard way of designating a neutral tap.