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 . Calculate the minimum value of firing angle if the motor drives a constant torque load requiring an average armature current of 30 A.

The speed of a separately excited dc motor is controlled below base sp

1.	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 . 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» C. 59/46