A double-cage of a 3-phase, 50-Hz, 4-pole induction motor, have the following equivalent circuit parameters, all...

 

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A double-cage of a 3-phase, 50-Hz, 4-pole induction motor, have the following equivalent circuit parameters, all of which are phase values referred to the stator and the stator impedance is negligible : Outer cage (R = 92, X = 2 ): Inner cage (R = 2 2, X = 8 (2). a) Calculate the ratio of torques produced by outer cage and inner cage at starting. b) What slip will the torque contributed by the two cages be equal? 2-The rotor resistance and reactance per phase of a 4-pole, 50-Hz, 3-phase induction motor are 0.025 ohm and 0.12 ohm respectively, calculate the value of external rotor resistance per phase to be inserted to obtain 75% of maximum torque at start. Q3//A single phase 230V, 50 Hz, two pole induction motor has the following constant in equivalent circuit: R1=2.22; XI-3.002: R2=3.82; X2=2.12; Xm=86 2. 1- If the motor is operating at full-load speed of 2820 rpm, calculate the input current and input power 2-If the mechanical losses are 50 W, calculate gross power developed and efficiency. Q4// Answer for the following question: 1-The armature of a 6600 volt, three-phase, 20-pole, 300 rpm star-connected alternator has 180 slots. The flux per pole is 80 m Wb and the coil span is 160° electrical. Determine the number of conductors in series per phase. 2-A 3-phase, star-connected alternator supplies a load of 10 MW at p.f. 0.85 lagging and at 11 kV (terminal voltage). Its resistance is 0.1 ohm per phase and synchronous reactance 0.66 ohm per phase. Calculate the line value of e.m.f. generated. A double-cage of a 3-phase, 50-Hz, 4-pole induction motor, have the following equivalent circuit parameters, all of which are phase values referred to the stator and the stator impedance is negligible : Outer cage (R = 92, X = 2 ): Inner cage (R = 2 2, X = 8 (2). a) Calculate the ratio of torques produced by outer cage and inner cage at starting. b) What slip will the torque contributed by the two cages be equal? 2-The rotor resistance and reactance per phase of a 4-pole, 50-Hz, 3-phase induction motor are 0.025 ohm and 0.12 ohm respectively, calculate the value of external rotor resistance per phase to be inserted to obtain 75% of maximum torque at start. Q3//A single phase 230V, 50 Hz, two pole induction motor has the following constant in equivalent circuit: R1=2.22; XI-3.002: R2=3.82; X2=2.12; Xm=86 2. 1- If the motor is operating at full-load speed of 2820 rpm, calculate the input current and input power 2-If the mechanical losses are 50 W, calculate gross power developed and efficiency. Q4// Answer for the following question: 1-The armature of a 6600 volt, three-phase, 20-pole, 300 rpm star-connected alternator has 180 slots. The flux per pole is 80 m Wb and the coil span is 160° electrical. Determine the number of conductors in series per phase. 2-A 3-phase, star-connected alternator supplies a load of 10 MW at p.f. 0.85 lagging and at 11 kV (terminal voltage). Its resistance is 0.1 ohm per phase and synchronous reactance 0.66 ohm per phase. Calculate the line value of e.m.f. generated.

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