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Power Factor

In AC systems, "Power Factor" is the ratio of volt-amps to watts. To get volt-amps, you also multiply volts times amps. With a resistive load, such as an incandescent lamp, volts times amps equals watts. All of the power gets dissipated heating up the lamp filament to make it glow. In this case, volt-amps is equal to watts, giving a ratio of 1:1, or 100%. With inductive loads like Transformers, electric motors, fluorescent lamps, etc., there is very little resistance. Something called "reactance" limits current flow. Larger currents flow with little power being dissipated. With a power factor of 50%, double the current would flow. For example, a 40 watt incandescent lamp draws 0.33 amps. (40 watts / 120 volts = 0.33 amps) This bulb, being a resistive load, has a power factor of 100%. A single tube fluorescent lamp rated at 40 watts may draw double the current of the 40 watt incandescent, but still only use 40 watts of real power. This fixture has a power factor of 50%.

Additional Input from Contributors:
  • Power Factor, simply put is a % of how efficiently the AC power is being used.

    THIS DOESN'T MATTER IN HOUSEHOLD ELECTRICITY. If a factory has a Power Factor of 95%, then it will draw 105% of the current it would draw if it were at 100%, or a Powerfactor of 1 (also called unity).The electric companies charge large industrial customers more for inefficient systems, i.e. Power Factor lower or higher than 1 (100% efficient). They do not charge individual homes for this, so you can't save money by correcting your power factor.

  • It's a ratio of AC volt-amperes to AC watts
  • Electrical meters for homes measure only resistive (real, apparent, or actual) power. They do not measure reactive power.
  • In a study of alternating current (that which supplies our homes and businesses in the United States), it will be observed that there are alternating waves of both voltage and current. In a circuit with purely resistance load, the waves of current and voltage are in exact phase relationship to each other. This means that when the voltage is at its peak, the current flow is at its peak as well. An inductive load (that is, a coil) causes the current wave to lag or fall behind the voltage wave, so that the peak current flow is some time after the voltage wave is at its peak level. A capacitive load (that is, a capacitor) causes the current wave to lead or advance ahead of the voltage wave, so that the peak current flow is some time in advance of the peak of the voltage wave.The consequence of this is that the AVAILABLE REAL POWER is the relationship between the current and voltage waves.
  • Resistive circuits have a power factor of 1.0, or unity, because the waves are in phase. The more out of phase the relationship between voltage and current, the less efficient the use of available power, the more "waste" energy.The less efficient the use of energy, the larger the size of transmission and generating equipment required to provide for energy needs and the more costly the operation of utilization equipment.
  • Power Factor is the relationship between Current and Voltage in an electrical supply With a power factor of 1 power equals Volts multiplied by Amps (I=VxA)

Also see the related Question WHAT IS REACTIVE POWER? by clicking on the link below:

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โˆ™ 2009-12-21 16:43:30
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Q: What does power factor mean?
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Related Questions

What mean power factor 0.26 lead?

When looking at power factor, it is the ratio of watts (true power) to VA. The power factor is how we measure power systems. A person with a low power factor like .26 will have a higher electricity bill.


What does power factor mean in math?

power factor is the cosine of the angular difference between current and voltage and must be taken into account to get true power (watts)


What does in a power the number used as a factor mean?

Numbers with exponents are sometimes referred to as a power. For example, x^4 can be called "x to the fourth power" which means that x is used as a factor four times. So, in a power, the number used as a factor is the base.


What does a Lagging power factor mean?

underdampedAnswerA lagging power factor describes a situation in which the load current is lagging the supply voltage. This describes an inductive load, such as a motor, etc.


Is pure inductor consumes energy?

Pure inductors consume and produce power, just like other reactive devices. The difference is that the current is not in phase with the voltage, resulting in the waveform of the power being oscillating about zero, with a net mean power of zero. In this "pure" case, the power factor is zero, but that does not mean there is no power - its just that the power "reading" is unsophisticated and not compensating for power factor.


What are power factor calculations?

As the name implies, these are calculations to determine the power factor of a load, where power factor is the ratio of a load's true power to reactive power.


How do you calculate actual power factor?

There are a number of different ways of determining the power factor of a load, depending on what information you have access to. For example:power factor = cosine of phase anglepower factor = true power / apparent powerpower factor = resistance / impedancepower factor = votage across resistive component / supply voltageetc.


What is the difference between unity power factor to 8 power factor?

Power factor does not go above 1. It is the cosine of the phase angle between voltage and current and, as such, can range between +1 and -1, although it should be understood that a negative power factor is mathematically equivalent to a generator - when looking at the load as if it is a motor - or vice versa. Unity power factor is applicable for a resistive load. A typical power factor for a big motor is about 0.92. A theoretical power factor of zero, corresponding to a phase angle of 90 degrees, would mean that the load is purely inductive or capacitive, and that the power supply and conductors are also ideal or theoretical.


What is the power factor of an induction motor?

what is the power factor of motor


How do you find power input with given power factor and power output?

Output Power divided by Power Factor.


What are the types of power factor meter?

there are 3 types of power factor meter: 1). electrodynamic power factor meter, 2).moving-iron power factor meter and 3). nalder-lipman moving-iron power factor meter.


What are the advantages and disadvantages of unity power factor?

There is no disadvantage of unity power factor, because at unity power factor all the electrical power is efficiently utilized by the the load, and at lagging power factor some power is lost in the load's magneticfield.


What are the advntage of the leading power factor?

there are no adwantage of leading power factor . always our aim is to get unity power factor , as at unity power factor reactive losses are zero.Yes if there are lagging loads then then we have to supply lagging var locally to make the power factor UPF.


What is the difference between displacement and true power factor?

'Displacement power factor' is the technically-correct term used to describe the cosine of the phase angle (i.e. the angle by which the load current leads or lags the supply voltage) due to the reactance of a load. Usually, when we talk about the 'power factor' of a load, we mean 'displacement power factor'.However, another type of power factor can exist in a circuit, due to the presence of harmonics in the current waveform, due to non-linear loads such as SCR rectifiers. This type of power factor is temed 'distortion power factor', and may be corrected using filters.So, the terms 'displacement' and 'distortion' are used whenever it is necessary to clarify these different types of power factor.


Why is power factor important and why would you want to improve it?

Effective Power = Volts x Amps x Power Factor Power Factor ranges from 0 to 1. At a Power Factor of 1 the load is pure resistive and the current and voltage are exactly in phase. As the voltage and current get out of phase the Power Factor decreases and you reduce the power. Therefore, a Power Factor of 1 is most efficient.


When will i use 0.82 power factor?

There is no significance to a power factor of 0.82.


What is the power factor of a circuit?

power factor means kw/kva


What is power factor of LCR series circuit?

Power factor is one


Why you use low power factor wattmeter on primary and unity power factor on secondary side of transformer?

There is no such thing as a 'low power-factor' wattmeter. A wattmeter always reads true power, regardless of the load's power factor.


Is a power factor capacitor different from a regular capacitor?

A power factor capacitor is a power capacitor. I'm not sure what you mean by "regular". There are different types, made from different materials that have better/worse characteristics than others depending on the application. You could use any high power capacitor for power factor correction, as long as it is sized correctly for the load and voltage.


What number is used as a factor in a power?

A base number is used as a factor in a power.


Papers on automatic power factor controller?

automatic power factor controller


Advantages of low power factor correction?

advantages of low power factor


Why generators are rated at 0.8 lagging power factor?

Rated power factor


What is PFI panel?

Power Factor Improvement Panel. It controls power factor