The floating star neutral to earth voltage in transformer.

[prc]

In a 131/11.5 kV three-phase Dyn Transformer, a balanced 10 kV was applied to the primary, with the secondary neutral floating. The voltages measured on the LV secondary were equal in all phases. The line to neutral voltages were 504 V, the line to earth voltages were 505 V, and the line to line voltages were 875 V. The neutral to earth voltage was 655 V. Why is the N_E voltage higher than the phase voltage? What does it signify?

 

[waross]

655 Volts is close to the average of 504V and 875V.
You are probably looking at capacitively coupled voltages of the average winding voltages.

 

[FPelec]

As said by waross, I also believe that the star point to ground voltage is due to capacitive coupling between the primary and secondary.