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Tham khảo tài liệu 'electric machinery fundamentals power & energy_2', kỹ thuật - công nghệ, điện - điện tử phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | R R R . R R _ TOT stator air gap 1 rotor air gap 2 At a flux density of 1.2 T the relative permeability Ar of the stator is about 3800 so the stator reluctance is 0.48 m Rstator z w.---------------__7T7Vz X 62.8 kA t Wb AstatorAtator O800 4nx 10-7 H m 0.04 m 0.04 m At a flux density of 1.2 T the relative permeability Ar of the rotor is 3800 so the rotor reluctance is R lrotor rotor A. . stator otor 0.04 m__ 3800 4nx 10-7 H m 0.04 m 0.04 m 5.2 kA t Wb The reluctance of both air gap 1 and air gap 2 is R R lair gap _0.0005 m__ 221 kAf wb air gap 1 Rair gap 2 . Í . _ 4 n-7 TT . n nn 4 2 221 kA t WD Air gap Air gap An 10 H m 0.0018 m Therefore the total reluctance of the core is R R_ R . R R . TOT stator air gap 1 rotor air gap 2 Rtot 62.8 221 5.2 221 510 kA t Wb The required MMF is . O 0Rtot 0.00192 Wb 510 kA t Wb 979 A t Since F Ni and the current is limited to 1 A one possible choice for the number of turns is N 1000. 1-18. Assume that the voltage applied to a load is V 208Z - 30 V and the current flowing through the load is I 5Z15 A. a Calculate the complex power S consumed by this load. b Is this load inductive or capacitive c Calculate the power factor of this load d Calculate the reactive power consumed or supplied by this load. Does the load consume reactive power from the source or supply it to the source Solution a The complex power S consumed by this load is S VI 208Z- 30 V 5Z15 a 208Z- 30 V 5Z-15 a S 1040Z- 45 VA b This is a capacitive load. c The power factor of this load is PF cos -45 0.707 leading d This load supplies reactive power to the source. The reactive power of the load is Q wsin6 208 V 5 A sin -45 -735 var 1-19. Figure P1-14 shows a simple single-phase ac power system with three loads. The voltage source is V 120Z0 V and the three loads are Z1 5Z30 Q Z2 5Z45 Q Z3 5Z- 90 Q 17 Answer the following questions about this power system. a Assume that the switch shown in the figure is open and calculate the .
