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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)


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What is a power factor?

 The Power Factor is an indicator of the quality of design and  management of an electrical installation. It relies on two very  basic notions: active and apparent power.

What is power factor?

The Power Factor is an indicator of the quality of design andmanagement of an electrical installation. It relies on two verybasic notions: active and apparent power. The act

What does a Lagging power factor mean?

underdamped   AnswerA 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,

What does unity power factor UPF mean?

  Unity power factor has a value of 1.0. This means the current and voltage waveforms are in phase. This is only possible if the net load is non-reactive (resistive). If t

How do you get power factor?

Single phase PF = Input Watts/Volts x Amps. Three phase PF =Input Watts/Volts x Amps x1.732. Additional Answer You can determine the power factor of a circuit using three in

Are load factor and power factor the same?

No Load factor is average power consumption rate divided by peak power consumption rate over a period of time. Power companies like customers who have very steady consumptio

What do you mean by wattless current and power factor in AC?

Watts = Current x Voltage x Power Factor In an AC circuit both the voltage and current are sine waves. When they are in phase (waveforms lie over top of one another) the PF is

What is the meaning of poor power factor?

Power factor is the cosine of angle between voltage and current that we all know. And the power factor should be unity or close to unity. Unless if we have the power factor n

What does zero leading power factor mean?

A 'leading' power factor indicates that the load current is leading the supply voltage. Since power factor is the cosine of the angle by which the load current either leads or