Question

Calculate the terminal voltage of Permanent Magnet DC motor having a resistance of 2 Ω and a full load current of 5 A with 20 V back e.m.f.

(a) 30 V

(b) 25 V

(c) 20 V

(d) 31 V

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The above asked question is from DC Motors in portion Characteristics of DC & AC Motors of Electric Drives

Answer 1

The correct choice is (a) 30 V

The explanation is: Permanent Magnet DC motor is a special type of motor in which flux remains constant. The terminal voltage can be calculated using the relation Vt = Eb+IaRa = 20+5×2 = 30 V.