(a) Describe types of DC motors with description and its equivalent circuit. (8 marks) (b) Illustrate types of power los

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A Describe Types Of Dc Motors With Description And Its Equivalent Circuit 8 Marks B Illustrate Types Of Power Los 1 (52.97 KiB) Viewed 30 times

(a) Describe types of DC motors with description and its equivalent circuit. (8 marks) (b) Illustrate types of power loses of a DC motor with description (4 marks) (c) Explain the purpose of brushes and rotor in a DC motor. (4 marks) (d) A 30hp separately excited DC motor is running initially at VA​=240 V,IA​=110 A and n=1800rpm,RA​=0.19Ω supplying a constant-torque load while the field circuit is supplied with voltage, VF​=240 V and Radj​=175Ω and RF​=75Ω. The armature voltage, VA​ can be varied from 120 to 240 V. (i) Sketch the equivalent circuit of the motor with proper labels. ( 2 marks) (ii) Calculate the no-load speed of this separately excited motor when and VA​ at 120 V,180 V and 240 V. Assuming no armature reaction effect. (4 marks) (iii) Analyze the effect if the field circuit opened while the motor is running. (3 marks)