I can just mention my expeirence with a transformer which has Primary 11 kV and Secondary 430 volts , 30 kAmp The tappings are on Primary for variation of secondary volrtage from 380 volt to 450 violt ( VFVV configuration ) . The trfr tripped while charging at normal tap . We changed to higher turn tap and charged the transformer with a time gap of 5 minutes. this has led us belief that the increase in turns has reduced the current at chraging . I will like to hear similar experiences .