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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 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? Correct Answer 6

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, γn-1 = 4/0.4 = 10. By substituting γ value, we get n = 6.

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