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Doubts on reactive power

  1. Aug 9, 2011 #1
    Yes I understand the definition of reactive power. It is the power that flows back and forth on transmission lines and does not do work(correct me). My question is, is reactive power useful? In what case reactive power has to be minimized as low as possible? I read an article about the importance of reactive power that it is required to maintain the voltage to deliver active power through transmission lines. Isn't p.f. 1, in other words zero reactive power, always what we want?
  2. jcsd
  3. Aug 9, 2011 #2


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    Reactive Power is the power that flows into and out of a Reactive Component (capacitor or inductor) as it discharges and charges in AC power. These components require current to charge, but this current does not contribute to the Real Power which is delivered to the load.

    This Reactive Power is not useful per se; but it is very necessary. It becomes useful when you have a highly inductive load and add capacitance to balance the power factor more closely towards 1, but it is not something that we want, as it means a proportion of the current we are supplying is doing nothing for us, while we still need to rate wires/cables large enough to handle this additional current and the heat it generates.

    Most of the time a distribution company will tell you what the requirements are for your power factor, and the appropriate penalties for not reaching it, and it is up to you to decide if it is cheaper to pay these penalties or install and maintain the technology to bring it back towards 1.
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