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How does reactive power oscillate back and forth?

  1. Oct 3, 2007 #1


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    Hello, i am trying to understand the concept of active /reactive /complex power and am having some trouble understanding how the reactive powere 'oscillates back and forth between inductor and source'.

    Ok, lets say i have a pure inductive load, i know that the power consumed is 0, and i understand the mathematics which prove this. But i also know its not 'actaully' 0, the power, reactive power, is continuously travelling back and forth between source and load. But how?

    Is it because of the voltage across the inductor causing a magnetic field to be created and when there is no more voltage drop across the inductor, the magnetic field collapses releasing this power it consumed in the first place? If so how does it release this power? is it due to the change of magnetic field (it collapsing) which induces current in the circuit?

    help please! :smile:
  2. jcsd
  3. Oct 3, 2007 #2


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    Staff Emeritus
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    The voltage and current are out of phase in inductors and capacitors. When the current changes in an inductor, there is a opposing EMF which is proportional to the change in current. Similar, there is a change in potential across a capacitor with is proportional to the stored charge, which changes with current flow.

    The power stored in the inductor and capacitor is not simultaneously available to the load. Motors (inductive loads) will alway store some of the electrical energy in their windings, and that power is not then available to the motor shaft.
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