GATE Electrical Engineering (EE) 2012 Solved Paper

A 220V 15KW 1000rpm shunt motor with armature resistance of 0.25  has a rated line current of 68 A and a rated field current of 2.2A. The change in field flux required to obtain a speed of 1600 rpm while drawing a line current of 52.8 A and a field current of 1.8A is