Answer Posted / pritish
first of all, starter is used to limit the starting current to a safe value. starter is used in rotating machines. in case of transformer, to protect the winding from high inrush current, the insulation is placed in the winding in a manner called, insulation grading. in this method, the two end terminals are placed with high graded insulation and the grading of insulation goes decreasing when we travel from end to middle of the winding. this is done because, in a transient period, the high current first links to the end terminal and then it comes to the middle terminal. as the time constant of transient is 5time constant, between that interval the high current would have vanished. hence no starter is used in transformer instead, insulation grading is used to protect it from surges.
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