ABSTRACT

Conventional definition of electrical engineering terminology, which were as per linear load scenario are changing now with more non linear loads being used by electricity consumers. Conventional terms like resistance, which was measured as DC resistance and normalized for 50 Hz needs to be re-looked again as in the cables, apart from fundamental current of 50Hz, other frequencies of currents are also present with considerable amplitude. Power factor, which was earlier measured as cosine of angle between current and voltage is now re-defined as true power factor where multiplication factor with distortion factor due to harmonics is also added.

For demand or kVA, which was calculated based on power triangle where two legs used to represent reactive power (kVAr and active power (kW) and hypotenuse used to represent apparent power or demand (kVA). This definition holds true for linear loads or where current and voltage waveforms are sinusoidal.

A power system, where loads are dominated by non linear loads, presence of harmonics generally will be considerable. Under such environment, a conventional power triangle will not give correct apparent power as there will be presence of other harmonic current and voltage in the system that will add to the apparent power.

There are utilities who are billing to their consumers on kVAh basis instead of kWh basis. The customer must keep in mind that if utility is billing on kVAh basis , he is essentially charging for poor power factor often impacted by presence of heavy reactive load as well as non linear loads causing severe harmonic distortion. So addressing reactive load demand by reactive compensation in linaer load environment or harmonic filtering in non linear load environment are the best ways to reduce your energy bill whether charged on two part basis including power factor penalty or single part kVAh basis.

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