Explain the need of power factor correction?

Answer 1

There are two types of power - real power and reactive power. Real power is power that is used, such as the power used to light a light bulb. Reacitve power is power that is held and released by a reactive element (capacitor or inductor), thus is not actually used to do any work. The reactive elements cause a phase shift between voltage and current, which manifests itself as a change in power factor.

Power companies must supply both reactive and active power. Total power is equivalent to sqrt( Reactive^2 + active^2). Not only do they need to supply the reactive power, their equipment must be sized to handle a larger total power. Reactive power is generated by installing extra equipment - capacitor banks or inductor banks - or by running generation in such a way that more reactive power is created (this will lower the power plants' real power output).

Depending on who the customer is, they may not be billed for the reactive power, thus the oversizing of equipment, and the supplying of reactive power does not generate any revenue (but costs them). If power factor is bad enough, the power company will lose money, and thus require power factor correction, or will bill on both real and reactive power usage.

It's simple economics (money)!

Answer 2

A poor power factor is typically the result of inductive load. Capacitors cause the opposite effect of inductors, so placing them in parallel with inductive loads will counteract the effects of the inductive load, bringing power factor closer to unity.

Answer 3

Low power factor results in the need to oversize equipment to supply the extra current. Either the power company will take care of this, and charge you a premium for the extra current (aften as a higher cost per kWh you use), or you can take care of it locally by adding pf correction equipment.

Answer 4

This is an angle b/w the voltage and current.

If the load current is taking (IL) the angle b/w the V/I vary by load current.

The PF led in the capacitors.

Lag in inductors.

Unit in resistor.

Our load's all mostly inductive,so we need im improving the PF.

Answer 5

A capacitor mainly acts as the source for reactive power.The inducing of reactive power improves the power factor.
Answer
By drawing a current that is in antiphase (opposite sense) with the current drawn by the inductive component of the load, thus reducing the amount of load current drawn.

Answer 6

A capacitor draws a leading current which is in anti-phase to the current drawn by the inductive component of the load, and the resulting load current will therefore be closer to being in phase with the supply voltage, thus reducing the phase angle or improving the power factor (cosine of the phase angle).

Answer 7

Because most power factor problems are a result of an overly inductive circuit. Capacitance is the opposite of inductance, and thus cancels out the excessive inductance.

Answer 8

A capacitor is connected across the line voltage to improve the power factor.