engineering recuitment GATE EE 2023-24 Test Series Electrical Machines DC Motor DC Motor Speed Control
At 50% of full load the armature current drawn by a dc shunt motor is 40 A when connected to a 200 V supply. By decreasing the field flux its speed is raised by 20%. This also causes a 10% increase in load torque. The armature resistance including the brushes is 1 ohm. Neglecting armature reaction and saturation the percentage change in field current will be
1
28.9%
2
24.6%
3
27.4%
4
21.6%