Advancement (Lead)
Introduction
power factor, f.d.p., of an alternating current circuit, is defined as the ratio between the active power, P, and the apparent power, S.[1] It gives a measure of the capacity of a load to absorb active power. For this reason, f.d.p = 1 in purely resistive loads.
Definition
Contenido
Se define el factor de potencia como la razón entre la potencia activa y la potencia aparente :.
Es importante distinguir la diferencia entre los términos factor de potencia () y , ya que no son exactamente lo mismo. En cargas lineales, ambos valores coinciden. Sin embargo, en cargas no lineales el y son distintos.
Se dice que:.
El dispositivo utilizado para medir el f.d.p. se denomina cosímetro.
Linear circuits
In linear circuits, where the currents and voltages are perfectly sinusoidal, we have:.
The f.d.p is the cosine of the angle formed by the phasors of the current and voltage "Voltage (electricity)"). In this case it can be seen that where Z is the equivalent impedance of the system. From this it can be understood as a measure of the ability of element Z to absorb active power. For ideal resistance: . For ideal inductance and capacitor:.
Just as the power triangle relates , , , and the , the impedance triangle (not shown in this article) relates , , (magnitude of the impedance), and the From this last triangle it follows that the power factor is also.
Nonlinear circuits
In nonlinear circuits the wave shape is not perfectly sinusoidal. Nonlinear loads create harmonic currents, which can be represented by total harmonic distortion (THD). In this case the apparent power would not only be composed of P and Q, but a third component would appear, the sum of all the powers generated by the distortion. This distortion component is called .
In this case, the power factor is:.
While it is calculated only with the fundamental components (without harmonics):
If it is the harmonic distortion rate, it is the fundamental component of the effective current, it is the total effective current and considering an ideal voltage source, then the relationship between the power factor and is:.