A 250 V, 500 rpm, dc, separately excited motor is driving a constant-load torque. The motor has a field constant K? = 4 Vs and an armature resistance of 1 ?. Ignore the frictional losses.
a. Calculate the full-load torque.
b. Determine the terminal voltage required to block (stop) the motor.
c. Determine the terminal voltage needed to rotate the motor at 100 rpm in the
reverse direction.
d. Calculate the motor speed while the motor is operating at the conditions of part
(c), and the polarities of the terminal voltage are reversed.
e. Sketch the speed-torque characteristics and show all the operating conditions.
The load torque is constant; therefore, the armature current is constant.
a. At full load, we have the above conditions:
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