3ACcircuit(交流电路).pptVIP

阅读教材136-140 For the case of a pure capacitor, the current leads the voltage by 90°, or the voltage lags the curent by 90°. VC chosen here as a reference. The phase angle between voltage and current is 90°, and the cosine of that angle being zero, the power factor forthe case of a pure capacitor is said to be zero power factor leading, since the current leads the voltage by 90°. Passage 3 AC circuit 21 Give a brief explanation 22 If a sinusoidal voltage is applied to an impedance with a phase angle of 0o, the resulting voltage and current waveforms will look like this: Given that power is the product of voltage and current (p = i e), plot the waveform for power in this circuit. Passage 3 AC circuit Passage 3 AC circuit 22 If a sinusoidal voltage is applied to an impedance with a phase angle of 0o, the resulting voltage and current waveforms will look like this: Given that power is the product of voltage and current (p = i e), plot the waveform for power in this circuit. 23 If a sinusoidal voltage is applied to an impedance with a phase angle of 90o, the resulting voltage and current waveforms will look like this: Given that power is the product of voltage and current (p = i e), plot the waveform for power in this circuit. Passage 3 AC circuit 24 What is the significance of the power value oscillating equally between positive (above the zero line) and negative (below the zero line)? How does this differ from a scenario where there is zero phase shift between voltage and current? A symmetrically oscillating power waveform represents energy going back and forth between source and load, never actually dissipating.  Passage 3 AC circuit 25 The three different types of power in AC circuits are as follows: S = apparent power, measured in Volt-Amps (VA) P = true power, measured in Watts (W) Q = reactive power, measured in Volt-Amps reactive (VAR) Explain the names of each of these power types. Why are they called apparent, true, and reactive?  Passage 3 AC c