Of course Yes it is different, it depends upon the type of motor i.e.. type of load using... Ex. If in industry require constant speed motor used Syn. motor, which will have different p.f., and for Induction motors lagging with Different p.f.
Yeah, It is different depending on the hours power, the accuracy of manufacturer, the operating speed and load, and the type of the motor. The power factor of induction motor which is commonly used in factories is about 0.87-0.9 lagging.
Working ,power factor mainly depends on working principle, design and type of motor, along with size. Induction motor, works on induction principle having lower power factor(.8 to.85 lag), than, same size synchronous motor working, on magnetic locking principle(.9to .95lag). Higher the magnetizing current needed, lowers power factor. The working power factor of cage type induction motor, would be lower than, same size motor with wound rotor. Induction motor working at lower speed, with higher torque are working at low power factor. Similarly induction motor working on low load is having, more bad(low) power factor than, the same capacity synchronous motor, working at same, low load.
As was mentioned before, the angle of this “power triangle” graphically indicates the ratio between the amount of dissipated (or consumed) power and the amount of absorbed/returned power. It also happens to be the same angle as that of the circuit's impedance in polar form. When expressed as a fraction, this ratio between true power and apparent power is called the power factor for this circuit. Because true power and apparent power form the adjacent and hypotenuse sides of a right triangle, respectively, the power factor ratio is also equal to the cosine of that phase angle. Using values from the last example circuit:
It should be noted that power factor, like all ratio measurements, is a unitless quantity.
For the purely resistive circuit, the power factor is 1 (perfect), because the reactive power equals zero. Here, the power triangle would look like a horizontal line, because the opposite (reactive power) side would have zero length.
For the purely inductive circuit, the power factor is zero, because true power equals zero. Here, the power triangle would look like a vertical line, because the adjacent (true power) side would have zero length.
The same could be said for a purely capacitive circuit. If there are no dissipative (resistive) components in the circuit, then the true power must be equal to zero, making any power in the circuit purely reactive. The power triangle for a purely capacitive circuit would again be a vertical line (pointing down instead of up as it was for the purely inductive circuit).
Power factor can be an important aspect to consider in an AC circuit, because any power factor less than 1 means that the circuit's wiring has to carry more current than what would be necessary with zero reactance in the circuit to deliver the same amount of (true) power to the resistive load. If our last example circuit had been purely resistive, we would have been able to deliver a full 169.256 watts to the load with the same 1.410 amps of current, rather than the mere 119.365 watts that it is presently dissipating with that same current quantity. The poor power factor makes for an inefficient power delivery system.
Poor power factor can be corrected, paradoxically, by adding another load to the circuit drawing an equal and opposite amount of reactive power, to cancel out the effects of the load's inductive reactance. Inductive reactance can only be canceled by capacitive reactance, so we have to add a capacitor in parallel to our example circuit as the additional load. The effect of these two opposing reactances in parallel is to bring the circuit's total impedance equal to its total resistance (to make the impedance phase angle equal, or at least closer, to zero).
Question is, why power factor of motors used, in factory are different??????
Bhupendra Desai : No, It's about, whether there is a way to calculate PF?
We always talk about cumulative Power factor in any factory. We never talk about individual motors, still if your interest is in individual motor than I think it is ideal to construct same motors. Practically we can't manufacture 100% same motors
For induction motor, power factor varies, considerably, from no load condition(magnetizing currents dominates, total current), to full load.In factory, mainly induction motor is used as drive, hence we consider the factory power factor, not of the individual motor.