Reactance to Power Factor

Introduction

Understanding AC Current, Reactance (how it occurs) and Power Factor

Alternating current (AC) is a type of electrical current in which the direction of the flow of electrons switches back and forth at regular intervals or cycles. Current, or flow of electric charge, changes direction periodically.

For example, in India, AC power supplied to homes has a frequency of 50 Hz, which means the current changes direction 100 times a second.

In Direct Current (DC) Circuits, only resistance restricts the flow of current.

In Alternating Current (AC) Circuits, there are other aspects that affect the flow of current.

Though similar to resistance, they do not actually consume any power,

But load the system with reactive currents, hence known as Reactance.

Reactance is caused when the alternating waves of voltage and current are out of phase with respect to each other.

It can be represented in the form of waves or a phasor diagram as follows

AC waveforms their phase relations, phase shift and phasor diagram

Reactance is of two types:

Relation Between Impedance, Resistance and Inductive Reactance with phasor diagram used in pfc, power factor, electrical engineerings image

Inductive reactance (XL): Inductive reactance arises from the opposing magnetic field created by a coil, inductor, or any component in the circuit whith opposes the change in current. This opposition causes the voltage across the inductor to lag behind the current by 90 degrees in phase.

Relation Between Impedance, Resistance and Capacitive Reactance with phasor diagram used in pfc, power factor, electrical engineerings image

Capacitive reactance (XC): Capacitive reactance arises from the electric field stored in a capacitor, which opposes the change in voltage. This opposition causes the current to lag behind the voltage by 90 degrees in phase.

Where total Reactance (X) = XL – XC

So, in circuits, we want the total reactance to be minimum to reduce power loss.

How reactance obstructs the flow of current & its relation with the phase angle between voltage and current.

All industrial and commercial loads are inductive in nature, leading to unnecessary loading of the system and energy loss, while performing no real work. To counter this, capacitive reactance from capacitors should be introduced to the circuit. This helps achieve a balanced system by minimizing total reactance, bringing it closer to zero.

Thus, capacitors help to reduce reactive currents and increase efficiency of the circuit.

To understand power factor in electronic circuits, The above phenomenon can also be described by the following Power Triangle

Power Triangle

Apparent Power: It is the total current drawn from the generator and is measured in volt amperes (VA)

Real Power: Also known as active power, it is the energy that is used to do actual useful work, and is measured in watts (W).

Reactive Power: Reactive power is the portion of electrical power that doesn't perform useful work, It occurs when voltage and current are out of phase with each other due to the energy stored in the electric and magnetic fields of inductive and capacitive loads. Measured in volt-ampere reactive (VAR), it flows back and forth between the load and power source.

Phase Angle (θ): Phase angle is the angle between apparent power and real power. It is the difference between the voltage and current waveforms in an AC circuit.

Lower the phase angle, lower the reactive power, and hence higher the active-used power in the circuit.

Power factor = cosine of the phase angle.

Power factor is a measure of how efficiently an electrical load is using power. A power factor of 1 means that the load is using all of the power that it is receiving. A power factor of less than 1 means that the load is not using all of the power that it is receiving, and some of the power is being wasted.

For Efficient Energy Usage High Power Factor (ie. close to 1) is important, as it reduces the amount of current needed to deliver the same amount of real power.
Improving Power Factor

Helps to lower energy bills and improve the efficiency of the electrical systems
Helps to increase equipment life and have a lower the environmental impact.
It also eliminate penalties on reactive energy applied by the energy suppliers to users with low PF and thus

AC Current, Reactance & Power Factor Simplified!

Introduction

Alternating current (AC) is a type of electrical current in which the direction of the flow of electrons switches back and forth at regular intervals or cycles. Current, or flow of electric charge, changes direction periodically.

Reactance is caused when the alternating waves of voltage and current are out of phase with respect to each other.

Reactance is of two types:

Inductive reactance (XL): Inductive reactance arises from the opposing magnetic field created by a coil, inductor, or any component in the circuit whith opposes the change in current. This opposition causes the voltage across the inductor to lag behind the current by 90 degrees in phase.

Capacitive reactance (XC): Capacitive reactance arises from the electric field stored in a capacitor, which opposes the change in voltage. This opposition causes the current to lag behind the voltage by 90 degrees in phase.

Where total Reactance (X) = XL – XC

Power Triangle

Apparent Power: It is the total current drawn from the generator and is measured in volt amperes (VA)

Real Power: Also known as active power, it is the energy that is used to do actual useful work, and is measured in watts (W).

Phase Angle (θ): Phase angle is the angle between apparent power and real power. It is the difference between the voltage and current waveforms in an AC circuit.

Power factor = cosine of the phase angle.

For Efficient Energy Usage High Power Factor (ie. close to 1) is important, as it reduces the amount of current needed to deliver the same amount of real power.
Improving Power Factor

Power Factor =

Real Power (W)

Apparent Power (VA)

Thus, When Real Power (W) = Apparent Power (VA) then the power factor is 1 or unity.

Introduction

Alternating current (AC) is a type of electrical current in which the direction of the flow of electrons switches back and forth at regular intervals or cycles. Current, or flow of electric charge, changes direction periodically.

Reactance is caused when the alternating waves of voltage and current are out of phase with respect to each other.

Reactance is of two types:

Inductive reactance (XL): Inductive reactance arises from the opposing magnetic field created by a coil, inductor, or any component in the circuit whith opposes the change in current. This opposition causes the voltage across the inductor to lag behind the current by 90 degrees in phase.

Capacitive reactance (XC): Capacitive reactance arises from the electric field stored in a capacitor, which opposes the change in voltage. This opposition causes the current to lag behind the voltage by 90 degrees in phase.

Where total Reactance (X) = XL – XC

Power Triangle

Apparent Power: It is the total current drawn from the generator and is measured in volt amperes (VA)

Real Power: Also known as active power, it is the energy that is used to do actual useful work, and is measured in watts (W).

Phase Angle (θ): Phase angle is the angle between apparent power and real power. It is the difference between the voltage and current waveforms in an AC circuit.

Power factor = cosine of the phase angle.

For Efficient Energy Usage High Power Factor (ie. close to 1) is important, as it reduces the amount of current needed to deliver the same amount of real power. Improving Power Factor

Power Factor = Real Power (W) Apparent Power (VA) Thus, When Real Power (W) = Apparent Power (VA) then the power factor is 1 or unity.

Causes of Poor Power Factor

Additional Causes:

For Efficient Energy Usage High Power Factor (ie. close to 1) is important, as it reduces the amount of current needed to deliver the same amount of real power.
Improving Power Factor

Power Factor =

Real Power (W)

Apparent Power (VA)

Thus, When Real Power (W) = Apparent Power (VA) then the power factor is 1 or unity.