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Power Factor Correction

Some basic facts:

  • Power factor correction is most cost effective when applied directly to the offending load(s).
  • Application at the service entry/panel benefits the utility but you will still have the same losses in your wiring.
  • Capacitive correction can make PF worse on loads already containing filter capacitors and rectifiers.
  • Subtle changes like reversing plugs and moving loads from one branch circuit to another can greatly affect PF of both branches.

    Is it worth the trouble to correct it?:

  • Severe PF problems can shorten the life of equipment and appliances.
  • Severe PF problems often indicate equipment malfunction or impending failure.
  • Utilities are not allowed (in most cases) to bill for unused (reactive) power but it can significantly affect demand costs.
  • Inexpensive, passive methods like moving plugs, etc. are, indeed cost effective.
  • Losses such as frozen perishable goods due to load failure may justify cost.

    How can mM help?:

  • Real time display shows PF conditions on each branch circuit and algebraic total instantaneously.
  • Making and keeping track of changes (passive methods above) can help you fine tune your total PF for better savings.
  • Small, inexpensive motor capacitors can be added to specific inductive loads if they are needed.
  • Small inductors (unused wall-warts) can be added to specific capacitive loads if they are needed.
  • Other devices and improvements can be immediately verified regarding their effectiveness.

    Power Factor Correction Scams:

  • While there may be exceptions, a single correction device at the service entrance is unlikely to show cost-effective savings.
  • While there may be exceptions, a device plugged in to an arbitrrary receptacle is unlikely to show cost-effective savings.
  • Theoretical justification does exist but the savings or return on investment is often exaggerated.