Q1. Consider a three-phase machine. The stator has 18 slots, with a 2-pole stator, 3-phase, double-layer,...

 

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Q1. Consider a three-phase machine. The stator has 18 slots, with a 2-pole stator, 3-phase, double-layer, 8/9th of full-pitch distributed winding. Each coil side contains 10 conductors. The rotor has 12 slots with a 2-pole, single-layer, full-pitch distributed winding, and each coil side contains 10 conductors, and all rotor coils are connected in series. The rotor diameter is D= 0.2 m, and the rotor axial length is l-0.3m. The stator phase currents are; 27 4л ia = I cosot, A; iB =I cos(ot- -), A; ic=I cos(ot-), A. 3 3 Assuming that the frequency of the supply is 50HZ: a) Draw the complete stator winding diagram. b) Draw the space distribution of MMF for an AC excitation applied to stator phase A at t-0, with I=20/13 Amps, and other phases carry no current. Give a general expression for the fundamental MMF distribution in space, FA1(0,t). Comment on the nature of the MMF waveform obtained by the single-phase AC excitation of phase A. c) Draw the MMF diagram at t =0; when all three phases are excited by balanced three- phase currents, with I= 20/v3, Amps. Give a general expression for the fundamental MMF distribution in space, F1(0,t). Compare the MMF diagram you obtain with what found in (b). d) Assume that a balanced three-phase ac excitation is applied to the stator winding with I = 20/V3, Amps. Calculate the open-circuit fundamental rms rotor induced voltage, when the rotor is stationary. Q1. Consider a three-phase machine. The stator has 18 slots, with a 2-pole stator, 3-phase, double-layer, 8/9th of full-pitch distributed winding. Each coil side contains 10 conductors. The rotor has 12 slots with a 2-pole, single-layer, full-pitch distributed winding, and each coil side contains 10 conductors, and all rotor coils are connected in series. The rotor diameter is D= 0.2 m, and the rotor axial length is l-0.3m. The stator phase currents are; 27 4л ia = I cosot, A; iB =I cos(ot- -), A; ic=I cos(ot-), A. 3 3 Assuming that the frequency of the supply is 50HZ: a) Draw the complete stator winding diagram. b) Draw the space distribution of MMF for an AC excitation applied to stator phase A at t-0, with I=20/13 Amps, and other phases carry no current. Give a general expression for the fundamental MMF distribution in space, FA1(0,t). Comment on the nature of the MMF waveform obtained by the single-phase AC excitation of phase A. c) Draw the MMF diagram at t =0; when all three phases are excited by balanced three- phase currents, with I= 20/v3, Amps. Give a general expression for the fundamental MMF distribution in space, F1(0,t). Compare the MMF diagram you obtain with what found in (b). d) Assume that a balanced three-phase ac excitation is applied to the stator winding with I = 20/V3, Amps. Calculate the open-circuit fundamental rms rotor induced voltage, when the rotor is stationary.