The speed of a separately excited dc motor is controlled below base speed by using a type-A SCR based chopper. The supply voltage is 220 V dc and the armature resistance is 0.5 Ω. Calculate the minimum value of firing angle if the motor drives a constant torque load requiring an average armature current of 30 A.
A. 1/2
B. 3/44
C. 59/46
D. 7/12
Answer:B
The speed of a separately excited dc motor is controlled below base speed by using a type-A SCR based chopper. The supply voltage is 220 V dc and the armature resistance is 0.5 Ω. Calculate the minimum value of firing angle if the motor drives a constant torque load requiring an average armature current of 30 A.
A. 1/2 B. 3/44 C. 59/46 D. 7/12