Question

For a DC machine, the armature slot pitch is 35mm and the diameter is 0.2m. What is the number of armature slots for the machine?

(a) 17

(b) 18

(c) 19

(d) 20

The question was posed to me by my school principal while I was bunking the class.

Query is from Design of Armature in division Thermal Design Aspects of Electrical Machines & D.C of Design of Electrical Machines

Answer 1

The correct option is (b) 18

To elaborate: Number of armature slots = (3.14*D)/Number of armature slot pitch

Number of armature slots = (3.14*0.2)/35*10^-3

Number of armature slots = 17.94 = 18(approx).