Question

Resultant ampere-turn distribution of a DC machine is given by _________

(a) ATresultant(∅) = ATf (∅) – ATa(∅)

(b) ATresultant(∅) = – ATf (∅) + ATa(∅)

(c) ATresultant(∅) = -ATf (∅) – ATa(∅)

(d) ATresultant(∅) = ATf (∅) + ATa(∅)

The question was asked in an interview.

Question is taken from Armature Reaction topic in chapter Armature Reaction of DC Machines

Answer 1

The correct option is (d) ATresultant(∅) = ATf (∅) + ATa(∅)

Explanation: The exact way to find the flux density owing to the simultaneous action of field and armature ampere-turns is to find the resultant ampere-turn distribution ATresultant(∅) = ATf (∅) + ATa(∅), where ∅ is the electrical space angle.