what is power factor?

Answer 1

Power factor is the term applied to power flow in ac circuits, that indicates the fraction of real power (Watts) carried in the overall flow of apparent power in the circuit.

In ac circuits, the phase angle of the current is independent of the voltage, and only the component of the current that is in phase with the voltage will result in delivery of real power.
The component of the current that is 90 degrees out of phase with the voltage yields reactive power.

If you just multiply volts X amps, you get apparent power (VA).
Volts X Amps X cos(phi) = real power (W), phi is the angle difference between the volts and amps.
Volts X Amps X sin(phi) = reactive power (VAR).

Then, power factor p.f. = cos(phi).

Note that three-phase circuits throw in a sqrt(3) factor for the use of line-to-line voltage and line current in the above equations, but p.f. is still cos(phi).

Answer 2

The power factor of an AC electric power system is defined as the ratio of the real power to the apparent power, and is a number between 0 and 1. Real power is the capacity of the circuit for performing work in a particular time. Apparent power is the product of the current and voltage of the circuit.

Where reactive loads are present, such as with capacitors or inductors, energy storage in the loads result in a time difference between the current and voltage waveforms. This stored energy returns to the source and is not available to do work at the load. A circuit with a low power factor will have thus higher currents to transfer at a given quantity of power than a circuit with a high power factor.Circuits containing purely resistive heating elements (filament lamps, strip heaters, cooking stoves, etc.) have a power factor of 1.0.

\phi\, is the phase angle between the current and voltage, then the power factor is equal to \left|\cos\phi\right|, and:

P = S |cos(phi)|

Answer 3

*http://en.wikipedia.org/wiki/Power_factor
Find everything here.


A power factor of one or "unity power factor" is the goal of any electric utility company since if the power factor is less than one, they have to supply more current to the user for a given amount of power use. In so doing, they incur more line losses. They also must have larger capacity equipment in place than would be otherwise necessary. As a result, an industrial facility will be charged a penalty if its power factor is much different from 1.

Industrial facilities tend to have a "lagging power factor", where the current lags the voltage (like an inductor). This is primarily the result of having a lot of electric induction motors - the windings of motors act as inductors as seen by the power supply. Capacitors have the opposite effect and can compensate for the inductive motor windings. Some industrial sites will have large banks of capacitors strictly for the purpose of correcting the power factor back toward one to save on utility company charges. >

-Power factor is a quantity which has important implications when sizing a UPS system and power
distribution equipment. Power is a measure of the delivery rate of energy and in DC (direct current)
electrical circuits is expressed as the mathematical product of Volts and Amps (Power = Volts x Amps).
However, in AC (alternating current) power system, a complication is introduced; namely that some AC
current (Amps) may flow into and back out of the load without delivering energy. This current, called
reactive or harmonic current, gives rise to an “apparent” power (Volt x Amps) which is larger than the actual
power consumed. This difference between the apparent power and the actual power gives rise to the power
factor. The power factor is equal to the ratio of the actual power to the apparent power. The apparent
power is expressed as the Volt-Amp or VA rating. Therefore, the actual power in any AC system is the VA
rating multiplied by the power factor.

Answer 4

The power factor of an AC electrical 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 in the closed interval of -1 to 1. A power factor of less than one means that the voltage and current waveforms are not in phase, reducing the instantaneous product of the two waveforms (V x I). Real power is the capacity of the circuit for performing work in a particular time. Apparent power is the product of the current and voltage of the circuit. 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. A negative power factor occurs when the device generates power, which then flows back towards the source, which is normally considered the generator.
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. The higher 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 where there is a low power factor.

Linear loads with low power factor can be corrected with a passive network of capacitors or inductors. Non-linear loads, such as 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.


https://www.electrikals.com/

Answer 5

Power factor is the difference between
apparent power: (what you see on your ammeter X the RMS Voltage,) and real power: (actual watts consumed - true instantaneous volt amps, or 'area under the curve`).
If can be expressed as a 'phase angle` (the difference between the peak amp.s and peak volts), or as a percentage of real power/ apparent power.
Phase angle is more useful in considering the nature of the problem.
Percent is more useful in efficiency computations.

Answer 6

Power Factor represents the offset in time between voltage and the total current and is defined as the cosine of that offset.

The components of motor current are load current and magnetizing current (adding those instantaneous values yields the total motor current). Also, because load current is in phase with voltage and magnetizing current lags voltage by 90 degrees, their sum will be a sine wave that peaks somewhere between 0 and 90 degrees lagging which is the motor current's offset (in time) from voltage.

Answer 7

its all about power.

Answer 8

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