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The vector-relationship between apparent power, true power, and reactive power is represented by a right-angled triangle, whose hypotenuse represents apparent power and whose adjacent represents true power. Since power factor is defined as 'the ratio of true power to apparent power', you will find that this ratio corresponds to the cosine of the angle between them.

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Q: Why power factor expressed in cosine angle?
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What is the power factor when the current and voltage are in phase?

The power factor of a load is the cosine of the angle by which the load current lags or leads the supply voltage. So if they are in phase (phase angle is zero), then the power factor must be unity (1).


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 lags the supply voltage (i.e. the load's phase angle), a cosine of 0 corresponds to a phase angle of 90 degrees. So, a power factor of 0 (leading) indicates that the load current is leading the supply voltage by 90 degrees, which means that the load must be purely capacitive.


Why inductor have low power factor?

An inductor has a low power factor because it is a reactive device, and the phase angle of the current with respect to voltage is not zero. In fact, power factor is the cosine of that phase angle, which means that a power factor of 1 means no phase angle, which means a resistive load. Anything else represents a reactive load and a power factor less than 1.In an ideal case, with perfect inductors and perfect conductors, the power factor would be zero, i.e. the phase angle would be 90 degrees lagging.


What is power factor of an R L series circuit?

Power factor in any circuit is the ratio of the load's true power to its apparent power. It's also the cosine of the phase angle. In L-R circuits, it's described as a 'lagging power factor', because the load current lags the supply voltage.


Why is power factor is cos of angle between voltage and current?

Power factor is the ratio of true power to apparent power -if you refer to the so-called 'power triangle', these correspond to the adjacent and hypotenuse of a right-angled triangle. The cosine of the angle between them is the ratio of hypotenuse (apparent power) to adjacent (true power). As the power triangle is derived from the voltage/current phasor diagram, this is exactly the same angle as that between load current and supply voltage.

Related questions

How are power factor correction units sized?

Power factor is the cosine of the angle by which the load current lags or leads the supply voltage. It is expressed as a per-unit value: e.g. 0.8; in the past it has been expressed as a percentage value , e.g. 80%.


Can power factor greater than 1?

not possible. power factor is an cosine angle between current and voltage...


How can you find the power factor?

Power factor is the cosine of the phase angle between voltage and current. It is also KW/KVA.


Why it is power fector of cos?

Power factor is the ratio of the angle between the voltage and current.In the power triangle cosine angle is the ratio between them...


How do convert KVA to KW?

kVA = kW divided by (power factor). The power factor is the cosine of the angle between voltage and current.


What is the power factor when the current and voltage are in phase?

The power factor of a load is the cosine of the angle by which the load current lags or leads the supply voltage. So if they are in phase (phase angle is zero), then the power factor must be unity (1).


Can power factor be more than one?

No. In the simple case of a linear circuit, the power factor is the cosine of an angle, and that can't be more than 1.


What is the power factor in pure inductors explain?

The power factor (cosine of phase angle) of pure inductor is zero because the phase angle between current and voltage is 90 degrees .If the value is substituted in the formula It will be zero.


What is the power factor of an resititive load?

Power factor is the cosine of the phase angle between voltage and current. In a resistive load, current is in phase, i.e. with a phase angle of 0 degrees, with respect to voltage. Cosine (0) is 1.


What is meant by Generator P.f?

the cosine of the angle between voltage and current of generator is called power factor (pf) of generator.


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 lags the supply voltage (i.e. the load's phase angle), a cosine of 0 corresponds to a phase angle of 90 degrees. So, a power factor of 0 (leading) indicates that the load current is leading the supply voltage by 90 degrees, which means that the load must be purely capacitive.


What is the symbol of power factor?

There is no SI symbol, as such, for power factor. As power factor is the cosine of the phase angle (the angle by which the load current leads or lags the supply voltage), power factor is normally written as 'cos' followed by the lower-case Greek letter we pronounce 'phi' (I've no idea how to type a Greek letter in this answer!).