Question

What is the formula of the ratio of the lower limit to upper limit of current with respect to the resistance?

(a) lower limit of current / upper limit of current = motor resistance / resistance to limit the starting current

(b) lower limit of current / upper limit of current = (motor resistance / resistance to limit the starting current)^1/number of resistance

(c) lower limit of current / upper limit of current = (motor resistance * resistance to limit the starting current)^1/number of resistance

(d) lower limit of current / upper limit of current = motor resistance * resistance to limit the starting current

This question was addressed to me in an interview for internship.

I want to ask this question from Motor Starters, Calculation of Resistance Steps & Design of Field Regulators topic in section Design of Small Electrical Machines, Starters and Field Regulators of Design of Electrical Machines

Answer 1

Right option is (b) lower limit of current / upper limit of current = (motor resistance / resistance to limit the starting current)^1/number of resistance

Explanation: The motor resistance, resistance to limit the starting current and number of resistance is calculated. On substitution the ratio of lower limit to upper limit of current is obtained.