Question

What is the formula for the mmf required for air gap?

(a) mmf required for air gap = 8,00,000 * air gap flux density * air gap constant / air gap length

(b) mmf required for air gap = 8,00,000 * air gap flux density * air gap constant * air gap length

(c) mmf required for air gap = 8,00,000 * air gap flux density / air gap constant * air gap length

(d) mmf required for air gap = 8,00,000 / air gap flux density * air gap constant * air gap length

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

Asked question is from Operating Characteristics in division Design of Single Phase Induction Motor of Design of Electrical Machines

Answer 1

Right choice is (b) mmf required for air gap = 8,00,000 * air gap flux density * air gap constant * air gap length

Easy explanation: The air gap flux density, air gap constant, air gap length are calculated first. On substitution, the mmf required for air gap can be obtained.