Question

What will be the γ value for starter taking 4 steps, where ratio of resistance at maximum allowable current to armature resistance is equal to 1.8?

(a) 1.2164

(b) 1.8

(c) 2.2468

(d) 0.8220

I have been asked this question at a job interview.

I need to ask this question from Starting of DC Motors topic in section DC Motors of DC Machines

Answer 1

The correct answer is (a) 1.2164

The best I can explain: γ is defined as the ratio of upper current limit to the lower current limit in starters of DC machine. γ ^n-1 = ratio of resistance at maximum allowable current to the armature resistance. Substituting values for n=4, we get γ=1.2164.