230V Phase to Neutral (3-phase star) is around 380V Phase to Phase (3-phase delta). Motors are designed for one, or both - Star-Delta starters put the same windings in Star to start off and then into Delta once the motor is running. This avoids large switch-on currents, amongst other things.If you put higher than the rated voltage on a motor winding it will draw more current than it is designed for. The windings will get hotter than normal and this may cause changes in the insulation properties of the varnish used to insulate the wires of the windings. This may cause the insulation to burn or break down, causing shorted turns or earthing in the windings. Shorted turns in any inductance are bad news, they will cause very high fault currents and either trip the protection or burn the motor windings out, sometimes spectacularly.Windings for one phase (or pair of phases) in a motor usually don't touch or are well insulated from windings for other phases. Shorted turns in a winding are far more likely to occur than phase-to-phase shorts between different windings.
