A starter is required for a 220-V shunt motor. The maximum allowable current is 55 A and the minimum current is about 35 A. The armature resistance of the motor is 0.4 Ω. What will be the number of sections of starter resistance required?(a) 5(b) 4(c) 6(d) 8I have been asked this question in a job interview.The question is from Starting of DC Motors in chapter DC Motors of DC Machines

A starter is required for a 220-V shunt motor. The maximum allowable c

1.	A starter is required for a 220-V shunt motor. The maximum allowable current is 55 A and the minimum current is about 35 A. The armature resistance of the motor is 0.4 Ω. What will be the number of sections of starter resistance required?(a) 5(b) 4(c) 6(d) 8I have been asked this question in a job interview.The question is from Starting of DC Motors in chapter DC Motors of DC Machines
Answer» RIGHT option is (c) 6 Easy explanation: I1=55 A, I2 =35 A So, γ= Ratio of UPPER limit to the lower limit = 55/35 = 1.57, R1= 200/55= 4 Ω Now, γ^n-1 = 4/0.4 = 10. By substituting γ value, we GET n = 6.

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