We
would discuss about** Power Factor** in this article. We discuss
so many questions about Power Factor like, what is Power Factor? Practical significance
of Power Factor, types of Power Factor, why do we need to improve Power Factor?
Methods of Power Factor improvement and so on

**Power Factor**

** **

There are so many definition of Power Factor which
introduced in so many books some of are given below

1) Power Factor is defined as the ratio of Active Power to Apparent Power and it is represented by cos@. Let us understand by Power Triangle

S =
Complex Power or Apparent Power

P =
Active Power

Q =
Reactive Power

J =
complex Operator

S = P
+ jQ _{(KVA)}

S^{2}
= P^{2 + }Q^{2}

P =
S*cos@ _{(watts)}

Q =
S*sin@ _{(VARs)}

So
cos@ = P/S

OR

2) Power
factor of an electrical circuit is the cosine of phase difference between the
voltage and current applied them.

**Cos( _{phase difference btw
voltage and current})**

** **

@ is
the phase difference between voltage V and current I.

Power
Factor cos@ lies between 0 to 1

**Practical
Significance of Power Factor **

Practically
we can say P.F. is the degree of complex power which we used actively. Means ,
let us consider P.F. is 0.8 means 80% of total power used actively and rest of
20% energy stored in inductor and capacitor in the form of magnetic energy and
electrostatic energy respectively.

** **

**Types
of Power Factor**

- Lagging Power Factor

- Leading Power Factor

- Unity Power Factor

**Lagging
Power Factor**

Lagging power factor indicates those loads which absorbs reactive power (lagging VARs). For such kind of loads load current is lagging from supply voltage. This property indicates that load is inductive in nature. The inductor stores the energy in the form of magnetic energy. To maintain this magnetic domain inductor absorbs lagging VARs. So we can say the power factor of inductive circuits is lagging.

**Leading Power Factor**

** **

Leading power factor indicates
those types of loads which supply reactive power (lagging VARs). For such kind
of loads load current is leading from supply voltage. This property indicates
that load is capacitive in nature. The capacitor stores the energy in the form
of electrostatic energy and it supplies lagging vars. So we can say the power factor of capacitive
circuit is leading.

**Unity Power Factor**

In a
purely resistive ac circuit the current and voltage are in same phase and phase
difference between current and voltage is zero.

Power Factor = cos0 = 1.

So we can say that the power
factor of pure resistive circuit is unity. Unity power factor indicates that it
neither supply reactive power nor absorbs reactive power it use 100% of
apparent power.

**Why
do we need Power Factor improvement?**

** **

** **

**P = VIcos@**

**I = P/Vcos@ **

** **

- I is
inversely proportional to cos@. If cos@
is increases then current I decreases means I
^{2}R losses decreases then efficiency increases.

- As I is inversely proportional to cos@. Higher the power factor lower the current flow means low cross sectional area conductor is required and thus it saves the money

- Higher Power factor means fraction of useful power is high.

- As Cos@ increases Sin@ decreases means reactive power burden on generator reduces

**Power Factor Correction / Power Factor Improvement Method**

** **

- Power factor improvement by Capacitor bank

- Power factor improvement by Synchronous condenser/Synchronous phase modifier

**Power
factor correction by Capacitor bank**

** **

Since
most of the practical load is inductive in nature. An inductor requires power
(reactive power) to maintain magnetic domain. If generator can’t able to supply
the reactive power demand then capacitor bank is connected in parallel to the
load. This capacitor bank fulfils the reactive power demand.

**Synchronous
Condenser/ Synchronous Phase Modifier**

** **

Synchronous
phase modifier is an overexcited synchronous motor on no load. Synchronous
machine can operate on all Power Factors like leading, lagging, unity according
to their excitation. By controlling the excitation of synchronous motor
reactive power demand and supply can maintain.

An
overexcited synchronous motor supplies lagging VARs (reactive power) which helps
to improve power factor

An
under-excited synchronous motor absorbs lagging VARs which helps to reduce
Ferranti effect.

__related posts__

**#_inductor**

**#_Resistor**

**#_Power**

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