Power factor complete article

POWER FACTOR:

The Power factor is a term associated with the Altenating current (A.c) circuits.The term does not applies in D.c circuits.

DEFINITIONS:

The ratio of  real power  to its apparent power derived by  circuit elements  is  termed as Power factor

MATHEMATICAL FORMULA:

We know that Real power through the A.c  component is

P=V*I*Cos@                eq.  no 1

The apparent power of an electrical component is given by

S=V*I                      eq. no 2

Putting the value of equation 2 in 1

P=power S* Cos@

Cos@=  P/S

UNITS:

Power factor has no units because it is the ratio of two same quantities.

POWER TRIANGLE AND POWER FACTOR:

The power triangle is a relationship between active,reactive and the apparent power using vectors. The real power (P) is taken along x or horizontal Axis and the Reactive Power is taken along Y or vertical axis. This can be shown in the figure below

The apparent power can be calculated be using The Pythagorus Theorem.

The Real power becomes the base, the reactive power becomes the perpendicular, the remaining thing is the hypotenuse , applying to it the pythagorus theorem,

(Hypotenuse) ²= (base)²  + (perpendicular⁾²

(S)² = (P)² + (Q)²

Where @ is an angle between real and apparent power, this @ is same as it is the angle between current and voltage.and this is actually the @ which helps us to determine the power factor of any electrical component.

POWER FACTOR VALUES AND ITS MEANINGS:

Power factor can have any value depending upon the load that is connected. It will always vary between  -1 t0 1.The higher the power factor means the system is moving towards the stability.

EQUAL TO  0:

When  power factor of system is zero this means that circuit  element is purely inductive or capacitive. The source feeds the system, and can be consumed if load is attached to the system.

LESS THAN 1 GREATER THAN 0:

The value of power factor must be very close to 1. If the value of power factor is close to 0 this means that load attached is  inductive  and is drawing the current from the system.

If power factor is close to 1 then this means that load attached is a capacitive load. This moves the system towards the stability.  

EQUAL TO 1:

The power factor having value 1 indicates that load attached to the circuit is a resistive load.

NEGATIVE VALUE:

When angle between current and voltage becomes greater than 90⁰, then value of power factor becomes negative. This happens only when load becomes source.

EFFECT OF LOAD ON POWER FACTOR:

There are 3 types of load

1.      Resistive load

2.      Capacitve load

3.      Inductive load

RESISTIVE LOAD:

The resistive load does not have any effect on power factor. This is due to the fact that voltage and current are in phase with each other.

CAPACITIVE LOAD:

Capacitors  have  voltage leading current.So if system has a power factor of 0.82,then after attaching a parallel load will lead this power factor to 0.83 or 0.84,due to the fact that voltage tries to minimize the angle between current and voltage.This decrease in the angle between voltage and current  increases power factor and moves  system towards stability.

INDUCTIVE LOAD:

Inductors are circuit elements in which current leads  applied voltage. Attachment of such elements in system moves system away from stability. Lets suppose that if system has initially power factor of 0.82 and if we attach an inductive load to it,then inductive load will increase angle between voltage and current and as a result, power factor decreases.

HOW CAN WE IMPROVE POWER FACTOR:

The power factor is of great importance to power companies. The consumer is always paying for the real power being consumed by him,but actually he is using the reactive power to which decreases the power factor, resulting in the loss to power companies.This power factor is also important for industries as they can be fined if they are not maintaining the power factor according to the demand of power company.To resolve this issue of power factor, power companies and industries uses capacitor banks.These capacitor banks can help in maintaining and improving the power factor. Some industries also uses synchronous motors to improve the power factor.