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40 V, 7 A, 70 rpm DC separately excited motor having a resistance of 0.3 ohms excited by an external dc voltage source of 4 V. Calculate the torque developed by the motor on half load.

40 V, 7 A, 70 rpm DC separately excited motor having a resistance of 0.3 ohms excited by an external dc voltage source of 4 V. Calculate the torque developed by the motor on half load. Correct Answer 18.10 N-m

Back emf developed in the motor during the full load can be calculated using equation Eb = Vt-I×Ra = 37.9 V and machine constant Km = Eb÷Wm which is equal to 5.17. Torque can be calculated by using the relation T = Km× I = 5.17×3.5 = 18.10 N-m.

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