IntroductionA three-phase, 4-pole, induction motor has the following characteristics:● Frequency 50 Hz● Line voltage 400V● Line current 8.5A● Efficiency 85%● Slip 4%● The line current lags the voltage by a phase angle of 350Use the information in the introduction to this question answer parts(a), (b) and (c).(a) Calculate the rotor speed of the motor
(b) Calculate the power factor of the motor
(c) Calculate the output power of the motor.
(a) N = 60fP(½ mark)= 60 x 502(½ mark)= 1500 rpm (½ mark)Slip speed = N x slip (½ mark)= 1400 x 4% (½ mark)= 60 rpm (½ mark)Rotor speed = N – slip speed (½ mark)= 1500 - 60 (½ mark)= 1440 rpm (1 mark)(b) pf = cosФ (½ mark)= cos 350= 0.8191 lag (½ mark)(c) Input power = √3 VL IL cosФ (½ mark)= √3 x 400 x 8.5 x0.8191(½ mark)= 4823 W (1 mark)Output power = input power x efficiency (½ mark)= 4823 x 0.85 (½ mark)= 4099 W