A 220 V, 1500 rpm, 11.6 A (armature current) separately excited motor is controlled by a single phase, full wave SCR converter. The armature resistance of the motor is 2 ohm. The ac source voltage is 230 V (rms) 60 Hz. Enough inductance is added to ensure continuous conduction for any torque greater than 25% of the rated value. (Ignore the rotational losses)
A.)Calculate the triggering angle for the speed of 1000rpm at the rated torque.
B.)Assuming that the torque is a fan-type, calculate the triggering angle for the motor speed of 900 rpm.
C.) Sketch the speed-torque characteristics showing the operating points of cases (A) and (B).