Yes. Power factor is a cosine related function. To understand this, you need to understand volt-amps versus watts...
Volt-Amps (VA) is volts times amps, which may seem to be the same as watts (W). This is true only for resistive loads, where the phase angle of volts is the same as that of amps. In that case VA is the same as W.
What happens with non-resistive or reactive loads, however, is that amps are not in phase with volts. In an inductive load, such as a motor, amps lags volts; while in a capacitive load, amps leads volts. In both of these cases, you cannot just multiply volts and amps to get watts, due to a phenomenon known as power factor; power factor being the ratio of apparent power to true power.
To visualize this, you need to draw the power circle. Since WikiAnswers does not presently support graphic images, please take a piece of paper and follow along with me...
Draw a circle. To make it easy to do the math, draw it centered at the origin, and pretend that it has radius of one. This way, the trigonometry is easy.
Consider that the radius of the circle is VA. (Do not confuse this with the trigonometry trick where we also consider the radius to be one.)
Now, pick a point on the circle. Twelve O'Clock is a purely resistive load, where volts and amps are in phase. Nine O'Clock is a purely inductive load, where amps lags volts by 90 degrees. Three O'Clock is a purely capacitive load, where amps leads volts by 90 degrees. In "normal" trigonometry, zero degrees is at 3:00 O'Clock, but, by convention, zero degrees when dealing with reactive power is accepted to be 12:00 O'Clock. Just keep the trigonometric identities straight in your mind.
In practice, with normal electric motors and all other things considered, we see a point on the circle at about 10:30 or 11:00 O'Clock. Let's pick 10:30, to make the math easy. So, draw a line from the origin to the upper left at an angle of 45 degrees with respect to the Y-Axis. Label this line VA.
Notice that VA is constant, no matter what the phase angle may be.
Now, draw two more lines; one from the point on the circle at 10:30 O'Clock straight down, perpendicular to and stopping at the X-Axis - label this line W, and one from that same point to the right, perpendicular and stopping at the Y-Axis - label this line VAR.
Label the angle of the first line with respect to the Y-Axis as phase angle. Positive meaning inductive, and negative meaning capacitive. Notice that, if you had a 45 degree capacitive load, intersecting at 1:30 O'Clock, the magnitude of the VAR line would be the same, though positive instead of negative, and the W line would still be the same.
Now, power factor is W / VA, the ratio of apparent versus true. In this case, since we picked 45 degrees as the phase angle - to make it easy - the ratio is 0.707, or the cosine of the phase angle.
A typical power meter will register less than the actual power. In the worst case of a purely inductive load, the power meter would register zero, though the VA is still what it always was. The power meter is "lying", due to the power factor - energy is still being transferred - and the equipment must be sized to handle it - that is why Transformers and other things are often rated in VA instead of W. (Actually, KVA instead of KW.)
Now, if you are interested, and most power companies, engineers, and electricians are, then look at VAR. That is volts-amps reactive. There is a VAR power factor as well, simply the sine of the phase angle. In this case, again with 45 degrees, it is the same as the normal power factor, 0.707, however, we normally would call that -0.707, to differentiate between VAR (inductive) and VAR (capacitive).
Note that, if your phase angle is more than plus or minus 90 degrees, we are actually talking about a generator, instead of a load.
In practice, the phase angle is more like 20 to 30 degrees, so the power factor would be slightly higher, and the reactive power factor would be slightly lower. Power companies penalize large customers for poor power factors by measuring it and compensating their power meters or accounts to consider the perceived loss in energy or, more correctly, the increase in actual energy use. Also, poor power factor causes degradation of voltage on power lines, so power companies compensate with capacitor banks, shifting the phase angle back closer to zero
It's all to do with trigonometry. Apparent power is the vector-sum of true power and reactive power, and you can think of these three quantities forming a right-angled triangle (an oversimplification, but good enough for our purposes). Power factor is defined as the ratio of true power to apparent power, which corresponds to the ratio of adjacent to hypotenuse of this right-angled triangle. This ratio is called a cosine.
not possible. power factor is an cosine angle between current and voltage...
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.
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.
the cosine of the angle between voltage and current of generator is called power factor (pf) of generator.
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!).
not possible. power factor is an cosine angle between current and voltage...
Power factor is the cosine of the phase angle between voltage and current. It is also KW/KVA.
kVA = kW divided by (power factor). The power factor is the cosine of the angle between voltage and current.
power factor is the cosine of the angular difference between current and voltage and must be taken into account to get true power (watts)
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.
Power factor is the ratio of the angle between the voltage and current.In the power triangle cosine angle is the ratio between them...
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.
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.
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).
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.
i know that static capacitors are used to improve the power factor. power factor should be high. Static capacitor supplies lagging reactive power. That means; the current I has 2 components they are magnetising Im (watless or waste current) and useful current Iw. Iw is in phase with voltage and Im is 90 degree away. Phase angle between them is phi 1. power factor is given by cosine of phi 1. phi angle should be less so that cosine of phi is high. To make phi angle less we use capacitor; this is nothing but power factor correction and capacitor used for this is called power factor correction capacitor. now when a capacitor is connected, it induces a current Ic 180 out of phase from Im and less in magnitude from Im. therefore, now the magnetising current is Im1=Im-Ic. due to this the phase angle reduces to phi 2. now the new power factor is cosine of phi 2. it is improved power factor.
Cosine to the negative first power and cosine cancel each other out because cosine to the negative first power is one over cosine, and one over anything times anything is just one.