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A 30hp separately excited DC motor is running initially at VA=240 V,IA=110 A and n=1800rpm,RA=0.19Ω supplying a const
Posted: Tue Jul 12, 2022 8:39 am
by answerhappygod
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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)