![]() ![]() All the power entering the loads is consumed. The blue line shows some of the power is returned to the grid during the part of the cycle labelled φIn a purely resistive AC circuit, voltage and current waveforms are in step (or in phase), changing polarity at the same instant in each cycle. Instantaneous and average power calculated from AC voltage and current with a lagging power factor ( φ=45, cos φ=0.71). ![]() 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 In such cases, active or passive power factor correction may be used to counteract the distortion and raise the power factor. Non-linear loads, such as rectifiers, distort the current drawn from the system. Linear loads with low power factor (such as induction motors) can be corrected with a passive network of capacitors or inductors. Because of the costs of larger equipment and wasted energy, electrical utilities will usually charge a higher cost to industrial or commercial customers where there is a low power factor. The higher currents increase the energy lost in the distribution system, and require larger wires and other equipment. In an electric power system, 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. Due to energy stored in the load and returned to the source, or due to a non-linear load that distorts the wave shape of the current drawn from the source, the apparent power will be greater than the real power. Apparent power is the product of the current and voltage of the circuit. Real power is the capacity of the circuit for performing work in a particular time. Since the units are consistent, the power factor is by definition a dimensionless number between -1 and 1.Power factorThe power factor of an AC electric power system is defined as the ratio of the real power flowing to the load to the apparent power in the circuit, and is a dimensionless number between 0 and 1 (frequently expressed as a percentage, e.g. The general expression for power factor is given by General case Schematic showing how power factor is calculated ![]() 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. Linear loads with a low power factor (such as induction motors) can be corrected with a passive network of capacitors or inductors. Power-factor correction increases the power factor of a load, improving efficiency for the distribution system to which it is attached. ![]() The higher currents increase the energy lost in the distribution system and require larger wires and other equipment. A negative power factor occurs when the device (which is normally the load) generates real power, which then flows back towards the source. A power factor magnitude of less than one indicates the voltage and current are not in phase, reducing the average product of the two. Due to energy stored in the load and returned to the source, or due to a non-linear load that distorts the wave shape of the current drawn from the source, the apparent power may be greater than the real power, so more current flows in the circuit than would be required to transfer real power alone. Apparent power is the product of RMS current and voltage. Real power is the average of the instantaneous product of voltage and current and represents the capacity of the electricity for performing work. In electrical engineering, the power factor of an AC power system is defined as the ratio of the real power absorbed by the load to the apparent power flowing in the circuit. For the firearms cartridge ranking system, see Power factor (shooting sports). ![]()
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