高等電機機械 報告者:朱振源 指導老師:秦純 教授

題目6.1 The nameplate on 460-V, 50-hp, 60-Hz, four-pole induction motor indicates that its speed at rated load is 1755 r/min. Assume the motor to be operating at rated load. a. What is the slip of the motor? b. What is the frequency of the rotor currents? c. What is the angular velocity of the stator-produced air gap flux wave with respect to the stator? With respect to the rotor? d. What is the angular velocity of the rotor-produced air gap flux wave with respect to the stator? With respect to the rotor?

題目6.1 part (a)  

題目6.1 part (b)  

題目6.1 part (c)  

題目6.1 part (d)  

題目6.2 Stray leakage fields will induce rotor-frequency voltages in a pickup coil mounted along the shaft of an induction motor. Measurement of the frequency of these induced voltages can be used to determine the rotor speed. a. What is the rotor speed in r/min of a 50-Hz, six-pole induction motor if the frequency of the induced voltage is 0.89 Hz? b. Calculate the frequency of the induced voltage corresponding to a four-pole, 60-Hz induction motor operating at a speed of 1740 r/min. What is corresponding slip?

題目6.2 part (a)  

題目6.2 part (b)  

題目6.3 A three-phase induction motor runs at almost 1198 r/min at no load and 1112 r/min at full load when supplied from a 60-Hz, three- phase source. a. How many poles does this motor have? b. What is the slip in percent at full load? c. What is the corresponding frequency of the rotor currents? d. What is the corresponding speed of the rotor field with respect to the rotor? With respect to the stator?

題目6.3 part (a)  

題目6.3 part (b)  

題目6.3 part (c)  

題目6.3 part (d) d. What is the corresponding speed of the rotor field with respect to the rotor? With respect to the stator? 同步轉速跟定子有關，因此轉子速度為1200 rpm 非同步轉速跟轉子有關，因此轉子速度為(1200-1112)=88 rpm

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