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Power factor
Power factor
[1] In electrical engineering, an AC power system's power factor (PF) is defined as the ratio of the real power absorbed by the load to the apparent power flowing in the circuit. Real power is the average of the instantaneous product of voltage and current and represents the capacity of the electricity for performing work.
[1] Apparent power is the product of VMS current and voltage, often higher than real power as energy is cyclically accumulated in the load and returned to the source or since a non-linear load distorts the wave shape of the current. Where apparent power exceeds real power, more current flows in the circuit than needed to transfer real power. Where the power factor magnitude is less than one, the voltage and current are not in phase, which reduces the average product of the 2. A negative power factor occurs if the device (normally the load) generates real power, which then flows back to the source.
[1] In electric power systems, a load with a low power factor draws more current than a load with a high power factor for the same amount of useful power transferred. The larger currents increase the energy lost in the distribution system and require larger wires and other equipment. Because of the costs of larger equipment and wasted energy, electrical utilities will usually charge a higher cost to industrial or commercial customers with a low power factor.
[1] Power-factor correction (PFC) increases a load's power factor, improving efficiency for the distribution system it's attached to. Linear loads with a low power factor (such as induction motors) can be corrected with a passive network of capacitors or inductors. Non-linear loads, like rectifiers, distort the current drawn from the system. In such cases, active or passive power factor correction may be used to counteract the distortion and raise the power factor. The devices for correction of the power factor may be at a central substation, spread out over a distribution system, or built into power-consuming equipment.
Definition
Definition
The power factor is mathematically defined as: PF = cosφ = R/Z, where
φ or θ = phase angle, the angle between the real and apparent power and its cosine value is the power factor
R = reactive power
Z =
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Power triangle
Power triangle
A power triangle is a right-angled triangle used in AC electrical circuits to graphically the relationship between the real, apparent, and reactive power.
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