A dc, separately excited motor has an armature resistance of 1 ?. When a dc supply of 100 V is applied to the motor, the armature current is 4 A and the motor speed is 300 rpm. A half-wave SCR converter is designed to control the motor speed. The supply voltage is 120 V (rms), and the triggering angle of the converter is adjusted to 60o . When the motor is loaded with a constant-load torque of 10 Nm, the conduction angle is 175o . Assume that the field current is constant.
a. Calculate the average speed of the motor.
b. If the triggering angle is 35o
and the average speed is 300 rpm, what is the
conduction period of the motor?
c. A full-wave SCR converter is designed for the same motor. If the triggering
angle is 50o and the conduction period is l20o
, what is the speed of the motor?
d. A sufficiently large inductance is added in series with the armature circuit of
the motor described in (c). Calculate the minimum triggering angle of the SCR in
order to run the motor at a speed of 100 rpm with continuous armature current.
When
With a half-wave converter,
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