Introduction to Power Factor Correction Capacitors and Power Factor Correction Circuits

This publication demonstrates capacitor-based power factor correction circuits and power factor correction capacitors (PFCs).

Part of the AC power consumed by the inductive load is used to maintain the magnetic reversal due to the phase shift between current and voltage.

This energy is not used to perform useful work and can be considered as wasted energy.

Power factor correction circuits are used to reduce reactive power and increase the efficiency with which inductive loads consume AC power.

Power factor correction capacitors are an essential component of power factor compensation circuits.

This article describes design considerations when using these components for power factor compensation.

Power factor correction capacitor circuit

Reactive Power of Inductive Load

Inductive loads such as chokes, motors, induction heaters, generators, transformers, and arc welding cause electrical delays, commonly referred to as induction.

This induction creates a phase difference between current and voltage.

As a result of the phase shift due to inductance, the signs of current and voltage may vary. In such cases, negative energy is generated and returned to the power grid.

 When two regain the same sign, they need the same amount of energy to generate a magnetic field.

The energy lost through the magnetic reversal of the inductive load is referred to as the reactive energy.

Inductive AC loads are broadly divided into linear and non-linear devices. For linear loads, the current and voltage waveforms have identical sinusoidal profiles.

On the other hand, non-linear loads draw current at different frequencies and thus the waveform of current and voltage varies. For most non-linear loads, the current waveform is usually non-sinusoidal.

Examples of linear electrical loads include heating equipment, motors, and incandescent lamps.

Non-linear devices include variable frequency drives, DC motors, programmable controllers, arc-type lighting devices, induction furnaces, power factor correction capacitors, uninterruptible power supplies, and personal computers.

Non-linear electrical loads are known to be a major source of harmonic distortion in distribution systems.

Power Factor

The efficiency with which electrical equipment or equipment consumes alternating current energy varies. Some loads use energy efficiently, while others waste a significant portion of the energy they consume.

Power factor is used to describe the efficiency with which a load consumes alternating current power. The range of this dimensionless quantity is 0 to 1.

The total AC power (commonly referred to as apparent power) consumed by an electrical device or device depends on two components: active power (active power) and passive power.

Active power is the power a device needs to perform a task. On the other hand, reactive force does not produce useful work. Active power is usually measured in kilowatts and reactive power is measured in kilovolt-amperes.

Power factor is equal to the ratio of the active power (active power) to the total power (apparent power) drawn by the equipment or electrical equipment.

We can prove mathematically that the power factor is equal to the sine of θ. The closer this ratio is to 1.0, the more efficient the device or device.

For an ideal electrical load, the power factor is equal to 1.0 (power factor of 1). This means that all the energy pulled by the load is used to do useful work. However, this is difficult to achieve with an actual electrical load.

Why is it difficult for an electrical load to achieve a power factor of 1?

Most electrical loads have unique ineffective characteristics that make it difficult to achieve the ideal power factor.

To overcome this limitation, a power factor correction circuit is added to the network to compensate for the invalid characteristics of the load.

Power Factor Correction (Correction)

An electrical load with a low power factor consumes more power than it needs to perform a task.

This can lead to significant power losses in the network and high losses in the transformers.

This increase in energy consumption increases the operating costs of equipment and facilities.

If the power factor is weak, the voltage drop in the distribution network will also be large. In industries where the power factor is less than a certain value, it is common for power providers to impose penalties.

Energy companies encourage industrial consumers to improve their power factor for several reasons.

First, by improving the power factor, you can significantly reduce your electric bill.

Second, the high power factor helps reduce the efficiency loss of the consumer transformer.

Third, adding a power factor correction system can increase the effective capacity of the consumer power grid.

Finally, high power factors help extend the useful life of electrical equipment.

The power factor compensation grid reduces the power required by the load and improves the overall power factor.

Compensation networks for electrical loads allow to achieve good power factors, usually 0.95-0.98. Power factors less than 0.85 are usually considered a low power factor by the power company. 

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