Power Factor

What do you mean power factor?
What is the use of Power Factor?

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rahulr30  

  • Member Since May-2008 | May 30th, 2008


Power factor is the ratio of Active ppwer to apparent power in sysytem,It is an index to see how much of the energy is actually being utilized to do useful work

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rahulr30

  • May 30th, 2008
 

Power factor is the ratio of Active ppwer to apparent power in sysytem,It is an index to see how much of the energy is actually being utilized to do useful work

Theoritically power factor is defined as a ratio of INPUT POWER to POWER CONSUMED. Controlling the power factor is very much important and it ranges from 0.5 to 0.8

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We know power factor(ie.Current lags or leads behind voltage by some angle,and cos of that angle is power factor)...If the power factor drops below 1,the current consumed increases with the decrease in power factor...(for instance,load with pf 0.2 consumes more current than that with 1)...This lagging or leading of current is mainly due to the storage of charges by the capacitors and inductors....

Power factor is useful,because they are  helpful in analysying the percentage of useful power of all the power supplied...

Rahul has defined correctly the definition of power factor.
but I would like to add some points regarding uses of power factor.
Power factor also gives the idea about the active power and recative power. If power factor is high its active power is higher in comparision with reactive power also if power factor is higher then the corresponding current rating will be lower so for same rating of machine we need lower current rating coil.

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saharesuraj

  • Aug 15th, 2010
 

1) P.F. : POWER FACTOR.(cos<)
2) Mathematically : P.F. = real power/apparent power.= P/S
     where, real power(P) = useful power.
     apparent power(S) = useful power(P) + reactive power(R).

3) Power factor is inversely proportional to apparent power(S) as shown above
and as the rating of generators, transformers are in KVA, their size will
increase with less power P.F.
4) If a certain load is connected to a generating station demanding constant
useful power but when the reactive power increases the pf go on decreasing which
is not acceptable.
5) To overcome this capacitor banks (rating=Kvar) are connected in parallel near
consumer premises which supply this reactive power. Thus maintaining constant
power factor.
6) Also consumer is need to maintain constant pf or else utility company can put
fine them.


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pf is the co-sine of phase angle b/w voltage and current.Generalley it is leading or lagging depanding on the load whether it is inductive(lag) or capactive(lead).Take voltage as reference the current leads or lags the applied voltage depanding on the pf of the circuit.If the pf is near to unity effeciency of the circuit is the high.Only for resistive loads the pf is unity for remaining all loads pf is less than one.

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