Three identical single-phase transformers, each of rating 20 kVA, 2300/230 V, 60 Hz, are connected Y/Y to form a three-phase transformer bank. The high-voltage side is connected to a three-phase, 4000 V, 60 Hz supply, and the secondary is left open. The neutral of the primary is not connected to the neutral of the supply. The voltage between the primary and the supply neutral is measured to be 1200 V