Difference between revisions of "Power factor/es"

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(Created page with "File:Powrefactorgraphs.png|thumb|right|''Arriba -''Una carga resistiva con un factor de potencia de 1. La corriente, la tensión, la potencia están todos sincronizados. <br...")
(Created page with "Hay varios tipos de carga de corriente alterna (CA), algunos de los cuales requieren tensión y corriente al mismo tiempo...")
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[[File:Powrefactorgraphs.png|thumb|right|''Arriba -''Una carga resistiva con un factor de potencia de 1. La corriente, la tensión, la potencia están todos sincronizados. <br /> ''Abajo -'' Una carga inductiva con un factor de potencia menor que 1. La corriente está retrasada (detrás) de la fase de la tensión. El área sombreada en amarillo representa la energía no consumida que se envía de regreso a la fuente.]]
 
[[File:Powrefactorgraphs.png|thumb|right|''Arriba -''Una carga resistiva con un factor de potencia de 1. La corriente, la tensión, la potencia están todos sincronizados. <br /> ''Abajo -'' Una carga inductiva con un factor de potencia menor que 1. La corriente está retrasada (detrás) de la fase de la tensión. El área sombreada en amarillo representa la energía no consumida que se envía de regreso a la fuente.]]
  
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There are various [[Special:MyLanguage/Electricity types#Alternating current|alternating current (AC)]] load types, some of which require voltage and current at the same time (resistive loads) and others that require voltage and current at different times (inductive and capacitive). Power factor (PF) is a number between -1 and 1 that can be applied to AC loads to describe to what degree their voltage and current demand (phases) are in sync. A load with a power factor of 1 (top graph at right) will have voltage and current peak simultaneously each cycle. A load with a power factor of less than 1 (bottom graph at right) will have voltage and current peak at different times each cycle.  
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Hay varios tipos de carga de [[Special:MyLanguage/Electricity#Corriente alterna|corriente alterna (CA)]], algunos de los cuales requieren tensión y corriente al mismo tiempo (cargas resistivas) y otros que requieren tensión y corriente en diferentes momentos (inductivo y capacitivo). El factor de potencia (PF) es un número entre -1 y 1 que se puede aplicar a cargas de CA para describir hasta qué punto su tensión y demanda de corriente (fases) están sincronizados. Una carga con un factor de potencia de 1 (gráfico superior a la derecha) tiene un pico de tensión y corriente simultáneamente en cada ciclo. Una carga con un factor de potencia de menos de 1 (gráfico inferior a la derecha) tiene un pico de tensión y corriente en diferentes momentos de cada ciclo.  
  
 
The power factor of loads becomes important when [[Special:MyLanguage/Inverter sizing and selection|sizing and selecting an off-grid inverter]]. A load with a power factor of less than 1 will require that the inverter supply current that exceeds the power rating of the appliance in order for it to work properly. This current is not included in the power rating of the appliance as it is not consumed by the load and is returned to the source. Power factor is therefore only factored into sizing the inverter, but is not relevant when sizing the [[Special:MyLanguage/PV module|PV source]] or [[Special:MyLanguage/Energy storage|energy storage system]].
 
The power factor of loads becomes important when [[Special:MyLanguage/Inverter sizing and selection|sizing and selecting an off-grid inverter]]. A load with a power factor of less than 1 will require that the inverter supply current that exceeds the power rating of the appliance in order for it to work properly. This current is not included in the power rating of the appliance as it is not consumed by the load and is returned to the source. Power factor is therefore only factored into sizing the inverter, but is not relevant when sizing the [[Special:MyLanguage/PV module|PV source]] or [[Special:MyLanguage/Energy storage|energy storage system]].

Revision as of 13:28, 23 March 2021

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Arriba -Una carga resistiva con un factor de potencia de 1. La corriente, la tensión, la potencia están todos sincronizados.
Abajo - Una carga inductiva con un factor de potencia menor que 1. La corriente está retrasada (detrás) de la fase de la tensión. El área sombreada en amarillo representa la energía no consumida que se envía de regreso a la fuente.

Hay varios tipos de carga de corriente alterna (CA), algunos de los cuales requieren tensión y corriente al mismo tiempo (cargas resistivas) y otros que requieren tensión y corriente en diferentes momentos (inductivo y capacitivo). El factor de potencia (PF) es un número entre -1 y 1 que se puede aplicar a cargas de CA para describir hasta qué punto su tensión y demanda de corriente (fases) están sincronizados. Una carga con un factor de potencia de 1 (gráfico superior a la derecha) tiene un pico de tensión y corriente simultáneamente en cada ciclo. Una carga con un factor de potencia de menos de 1 (gráfico inferior a la derecha) tiene un pico de tensión y corriente en diferentes momentos de cada ciclo.

The power factor of loads becomes important when sizing and selecting an off-grid inverter. A load with a power factor of less than 1 will require that the inverter supply current that exceeds the power rating of the appliance in order for it to work properly. This current is not included in the power rating of the appliance as it is not consumed by the load and is returned to the source. Power factor is therefore only factored into sizing the inverter, but is not relevant when sizing the PV source or energy storage system.

Calculating power factor

There are different types of power that are used to determine the power factor for a load.

Power factor (PF) = Real power ÷ Apparent power

  • Real power is power that is used to perform work. This power is consumed and is measured in watts (W).
  • Reactive power is power that is power that does not perform work but is still present in a circuit. This power returns to the source and is measured in volt-amperes or volt-amps (VA).
  • Apparent power is the total power present in a circuit. Apparent power is the sum of real power and reactive power. Measured in volt-amperes or volt-amps (VA).

If the current and voltage of a circuit are measured for a circuit with a multimeter and multiplied this will be a measurement of apparent power. Devices specifically designed to measure power consumption, like a Kill-A-Watt meter, can measure real power.

Examples of different load types

Common resistive loads are incandescent light bulbs or an electric heater. These loads will have a power factor of 1, which is also referred to as unity power factor.

Example 1: A 40 W incandescent bulb is operating on a 120V AC circuit. You measure the current and get .3 A. What is the power factor for this light bulb?
  • Power factor = 40 W ÷ (120 V × .3 A) = 1
  • All power is consumed by the load.

Common inductive and capacitive loads are fans, televisions, radios, laptops, blenders, refrigerators, and LED lighting. These loads will have a power factor less than 1.

Example 2: A 20 W laptop is operating on a 120 V AC circuit. You measure the current and get .3 A. What is the power factor for this laptop?
  • Power factor = 20 W ÷ (120 V × .3 A) = .5
  • 20 W is consumed by the load the rest is reactive power that returns to the source.

Power factor estimates

Power factor values vary significantly between makes and models of appliances and it can be quite difficult to find specific values. The values in the chart below are conservative estimates.

Load Estimated power factor
LED bulb .45
Radio .9
Cell phone charger .45
LED TV .55
Laptop charger .5
Refrigerator .5
Blender .8
Printer - idle .4
Printer - printing .65
Electric water heater .97
Fan .87
Microwave .9
Projector .9

Notes/references

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