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Cost Implications Of Low Power Factor

  1. Jan 20, 2009 #1
    We operate a 3 phase, 11kV network with automatic power factor correction equipment installed. Over the last four weeks we have had the PFC switched off due to an electrical incident.
    How can I calculate the cost of running without PFC for this period of time, our load is fairly constant at around 2.5MW. Our manager wants to include the increased electricity cost on the insurance claim due to operating without PFC.

  2. jcsd
  3. Jan 21, 2009 #2


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    Last edited by a moderator: Apr 24, 2017
  4. Jan 21, 2009 #3


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    To see this from the Utility's point of view, remember what your uncorrected load is doing: forcing the Utility to supply you surplus current for the same power draw. This doesn't immediately cost them anything, unless it happens to force them to up the current rating of their distribution equipment in the locale of your facility.

    You should have some idea of the uncorrected power factor from the rating on the correction equipment installed. The cost, if any, will depend on the particular utility. Typically total cost is broken down into Distribution Demand in kw (power rating of the distribution to your facility) and another part reflecting actual energy supplied. Dominion Power for instance has an http://www.dom.com/customer/pdf/va/vab8.pdf" [Broken]Stay above that and there's no penalty. Drop below it and for your Distribution Demand cost, they charge a minimum of 85% of your maximum KVA demand. If your facility's max VA demand peaks up to, say, 3000 KVA, they may charge you for 2.55MW worth of distribution regardless of actual load. If your utility invokes such a trigger it will be no doubt be reflected in the next bill as a new floor for your 'Distribution Demand' as it is called with the supply portion remaining at the 2.5MW average. The cost difference between that bill and earlier ones, with the reason indicated on the utility bill, should be easy to demonstrate for your insurer.
    Last edited by a moderator: May 3, 2017
  5. Jan 21, 2009 #4
    I have managed to get a look at earlier bills and there is a charge for kVAr, it varies quite a bit, but I'm expecting a big jump due to PFC being turned off. I am thinking along the correct lines?
  6. Jan 21, 2009 #5


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    Yes, you are. The purpose of the power factor correction is to reduce the kVAr.
  7. Jan 21, 2009 #6


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    Would there be a way to install a kvar-hr meter?
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