Motor connection STAR or DELTA ?

Because that is the way the motors were made.

guest; the windings determine connection, example coils wound for 230 volt ac could be hooked up for 230 volt delta, or 400 volt star/wye connection, making it a dual voltage motor or if it is a large HP motor it could be hooked up for reduced voltage starting. perry

guest; i may not been real clear on my answer to your question? in the USA most 3 phase motors are wound with dual windings, for 230 volt or 460 volt depending upon the connections the basic winding is star/wye numbered phases 7,8,9, the other 3 windings are numbered 1&4, 2&5,3&6, tie 4,5,6 together, connect 1&7, 2&8, 3&9, 3 phase 230 volt star connected, for 460 volt. tie 4to7,5to8,6to9, for a star/wye connected 460 volt 3 phase motor. many countries use a 3 winding motor with 6 connections for delta 230 volt or star/wye connected 380 volt 3 phase 50 HZ Perry

as we know in star connection I phase = I line and in delta V phase = V line. so , in HT motors when we connect in delta, I line = 1.732 * I phase. so i will draw high current as a result , it will reduce the insulation life of the winging. thats why we connect in star. and this will not come for the LT motors.