Electrical Drives and Controls (EDC) MCQs | Page - 7

 the resistor is a linear element. it only absorbs real power and dissipates it in the form of heat. the voltage and current are in the same phase in case of the resistor so the angle between v & i is 90°.

 in the rotor injection method, when an external voltage is in phase with the main voltage net voltage increases and the value of slip decreases and the value of rotor speed increases.

 r.m.s value of the periodic square waveform is vm and r.m.s value of the trapezoidal waveform is vm÷3½. the peak value of the periodic square waveform is vm.

 given a number of poles = 2. rotor speed is 550 rpm.

 in the rotor injection method, when an external voltage is in opposite phase with the main voltage net voltage decreases and the value of slip increases and the value of rotor speed decreases.

 rotor injection method comes under slip changing technique. it uses an external voltage source to change the slip value. the load torque remains constant here.

 slip recovery scheme comes under the synchronous speed changing technique. it uses an external induction machine to change the frequency value. the load torque remains constant here.

 the slope of the v-i curve is resistance. the slope given is 9.1° so r=tan(9.1°)=.16 Ω. the slope of the i-v curve is reciprocal of resistance.

 at low values of slip, the electromagnetic torque is directly proportional to slip value. due to heavy loading slip value decreases which increases the ratio of r2÷s.

 the fundamental time period of