![]() ![]() ![]() It may be more than just the 2% as it reflects not only the cost of the fuel to produce the Apparent Power, but also the size of the generators, wires and transformers being the electricity infrastructure necessary to cope with that higher amount of Apparent Power. However, if you are billed in peak VA Demand and/or VAh Consumption, the reduction in Power Factor as a result of the increase in Apparent Power will cost you at least an extra 2% on your electricity bill. If you are billed in peak W Demand and/or Wh Consumption, any change in Power Factor between Scenario 1 and Scenario 2 will not change your energy bill since the REAL Power is the same in both scenarios. Generating vars is a waste of energy compared to using just enough to do the real work in Watts. This increase in Apparent power in order to supply the same REAL Power is the reason we try to bring PF as close as possible to unity. supplied energy, is converted to REAL Power (P). In this example, Power Factor = 0.98 means that 98% of the total Apparent Power (S), i.e. Power Factor = REAL Power / APPARENT PowerĪnother way of understanding what Power Factor means is as a percentage indicating energy conversion efficiency. If the load is partially inductive – say a motor, still required to do 200 Watts of Real Power component to drive its load, but it also has an inductive impedance component (therefore current lags voltage) equivalent to 40 varĪpparent Power S = 200 – j40 = 203.96 VA at an angle of -11.31 degreesĬonsidering Trigonometry, Power Factor is the ratio of the length of the base divided by the length of the Hypotenuse. In reality Complex Power would flip the triangle upside down compared to the following diagrams. Complex Power however remains in its correct Quadrant for the relationship between V and I.įor simplicity the following discussion on this page (erroneously) uses Apparent Power simply because when Voltage is the reference vector at angle zero, the angle of the Apparent Power S happens to be at the same angle as the current so visually it is easier to follow. when clearly Q should be zero and the S should lie on the east/west axis for power. This is fully described in /wiki/spaces/AP/pages/78479362Īs an example, in the spreadsheet attached to that page, setting the reference vector to say 60° but with a pure resistive load results in Apparent Power S appearing at the angle of the reference vector. However the net effect of that is that Q is positive for an inductive load. The reason we need to use I* is that just using I results in the S vector moving around the P:Q plane depending on the angle of the reference vector and whether I is with respect to V, or V is with respect to I. To note that there are two definitions of S in IEEE 1459: 2010 Scenario 2 Power Factor of an Inductive Load Power Factor = cos(Theta) = cos (0) = 1.0 Then we can also calculate Power Factor as: Power Factor = Magnitude of REAL Power / Magnitude of APPARENT Power since current is in phase with the volts, Phi = 0 We also know that REAL Power (Watts) is the resistive axis quadrature component of the Apparent Power, which is obviously perfectly in phase with the S vector, which is perfectly in phase with the Current vector which is perfectly in phase with the voltage vector, i.e. Apparent power = 200 VA in phase with the current vector (and voltage vector) Mathematics operations state that multiplying vectors, you multiple the magnitude and add the angle We can now define Apparent Power (some may call this Total Power) as S If the load is purely Resistive as say 50 Ohms, the current will be exactly in phase with the voltage with magnitude of two amps in accordance with Ohm’s Law, then we have a current vector referenced as: Voltage vector = 100<0 Scenario 1 Unity Power Factor If we take the Voltage vector as the reference of zero degrees phase angle, then as an example we have a voltage of 100 volts referenced as: Phi is the angle between one vector and another reference vector. General vector notation is a Magnitude and Angle with respect to some reference: ![]() IEC 8000-6 defines Power Factor as the ratio of the MAGNITUDE (absolute value) of Power (W) to the MAGNITUDE (absolute value) of apparent power (VA). ![]()
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