Question

230V, 10A, 1500rpm DC separately excited motor having resistance of .2 ohm excited from external dc voltage source of 50V. Calculate the torque developed by the motor on full load.

(a) 13.89 N-m

(b) 14.52 N-m

(c) 13.37 N-m

(d) 14.42 N-m

The question was posed to me in my homework.

This key question is from Dynamics topic in portion Dynamics of Electrical Drives of Electric Drives

Answer 1

Correct option is (b) 14.52 N-m

To explain: Back emf developed in the motor during full load can be calculated using equation Eb = Vt- I*Ra = 228 V and machine constant Km = Eb / Wm which is equal to 1.452. Torque can be calculated by using the relation T = Km* I = 1.452*10 = 14.52 N-m.