It's actually cos phi, where the Greek letter, 'phi', is the symbol for phase angle -the angle by which a load current lags or leads the supply current in an a.c. system (the Greek letter, 'theta', is used for the displacement of instantaneous values of current or voltage from the origin of a sine wave).
The reason why power factor is a cosine requires you to understand the relationship between apparent power, true power, and reactive power. Apparent power is the vector sum of true power and reactive power, and can be represented, graphically, by the so-called 'power triangle'. In the power triangle, true power lies along the horizontal axis, reactive power lies along the perpendicular axis, and the apparent power forms the hypotenuse, and the angle between true power and apparent power represents the phase angle. By definition, power factor is the ratio between true power and apparent power, and this ratio corresponds to the cosine of the phase angle.
From this, we can conclude that true power = apparent power x cos phi, where 'cos phi' is the 'factor' by which we must multiply apparent power to determine true power -i.e. the 'power factor'.
First of all, you can only measure power factor of a three-phase load, provided that it is balanced load. The power factor can then be found by determining the cosine of the phase angle, using the following equation:tan (phase angle) = 1.732 ((P2-P1)/(P2+P1))...where P1 and P2 are the readings of the two wattmeters.
'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.
Total 3-phase real power = sqrt(3) x VLL x ILL x cos (theta) = 3 x Vp x Ip x cos (theta) Total 3-phase reactive power = sqrt(3) x VLL x ILL x sin (theta) = 3 x Vp x Ip x sin (theta) where: ?LL denotes line-to-line and ?p denotes phase-to-ground quantities Therefore, S = sqrt( P2+Q2) = = sqrt[32 x Vp2 x Ip2 x cos2 (theta) + 32 x Vp2 x Ip2 x sin2 (theta)] = sqrt[32 x Vp2 x Ip2 x {cos2 (theta) + sin2 (theta)}] = sqrt[32 x Vp2 x Ip2 x {1}] = 3 x Vp x Ip (works for the line-to-line case, as well) Hope this helps, Chris
using vienna rectifier
p.f=kW/kV.A
When used to indicate angles, "theta" is an unknown (exactly like using "x" for the unknown in equations).
The angle between two vectors a and b can be found using the dot product formula: a · b = |a| |b| cos(theta), where theta is the angle between the two vectors. Rearranging the formula, we can solve for theta: theta = arccos((a · b) / (|a| |b|)).
Using these two measurements you would calculate the angle using the tangent. In this case: tan (theta) = 1680/2700
To find the measure of a central angle in a circle using the radius, you can use the formula for arc length or the relationship between the radius and the angle in radians. The formula for arc length ( s ) is given by ( s = r \theta ), where ( r ) is the radius and ( \theta ) is the central angle in radians. Rearranging this formula, you can find the angle by using ( \theta = \frac{s}{r} ) if you know the arc length. In degrees, you can convert radians by multiplying by ( \frac{180}{\pi} ).
A x B = |A| |B| sin[theta]
The sine of an angle theta that is part of a right triangle, not the right angle, is the opposite side divided by the hypotenuse. As a result, you could determine the hypotenuse by dividing the opposite side by the sine (theta)...sine (theta) = opposite/hypotenusehypotenuse = opposite/sine (theta)...Except that this won't work when sine (theta) is zero, which it is when theta is a multiple of pi. In this case, of course, the right triangle degrades to a straight line, and the hypotenuse, so to speak, is the same as the adjacent side.
First of all, you can only measure power factor of a three-phase load, provided that it is balanced load. The power factor can then be found by determining the cosine of the phase angle, using the following equation:tan (phase angle) = 1.732 ((P2-P1)/(P2+P1))...where P1 and P2 are the readings of the two wattmeters.
mgsin (theta) - (static) mu * mgcos(theta) = 0 rearrange the equation and cancal mg therefore, tan ( theta) = mu (static) theta = arctan (static mu) If the static coefficient is 0.57, then theta = arctan (0.57) theta = 29.7 degree Note: from the equation, the mass of the block is independent to the angle. Whether you have a bigger block or smaller block, it will start sliding @ 29.7 degree.
The acceleration of an object on an incline is influenced by the angle of inclination. A steeper incline will result in a greater component of the object's weight acting parallel to the incline, leading to a greater acceleration. The acceleration can be calculated using the formula a = g * sin(theta), where "a" is the acceleration, "g" is the acceleration due to gravity, and "theta" is the angle of inclination.
'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.
The frictional force that opposes the motion of an object on an inclined plane is given by the formula:Ffriction = (mu)N,where mu (the Greek letter mu) is the coefficient of friction, and N is the Normal force, which is the force equal and opposite to the component of the object's weight perpendicular to the surface of the incline.The Normal force will be equal to Wcos(theta), where W is the weight of the object (W= mg) and theta is the angle of the incline.When motion down the plane is impending (that is, a split second before the friction is overcome and the object starts to slide down the plane), Ffriction is equal and opposite to the component of the weight parallel to the surface of the plane. That component is equal to Wsin(theta).So, what does that give us?We know that(1) Ffriction = Wsin(theta)(2) Ffriction = (mu)N(3) N = Wcos(theta)Substituting for N in equation (2) gives usFfriction = (mu)Wcos(theta).Equating equ. (1) and (2) gives usmuWcos(theta) = Wsin(theta).Solving for mu gives usmu = sin(theta)/cos(theta)mu = tan(theta)theta = tan-1(mu) or theta = arctan(mu)So, the arctangent of mu is the angle of incline.(I guess I coulda just said that right from the beginning.)
Work done can be calculated using the formula: work = force * distance * cos(theta), where theta is the angle between the force and the direction of movement. The time interval does not play a direct role in determining work done. However, if you know the power (work done over time), you can calculate work done by multiplying power by time.