Lagging Power Factor Causes, Effects, Improvements


Power Factor of an Electrical system indicates how much part of a power supply is used by the load and how much part is wasting. For example, an induction motor has a 0.6 power factor rating. When that induction motor is connected to an AC supply, it will take only 60 percent of applied power supply to perform the mechanical work, rest 40 percent of the applied power is wasting.

So, the measurement, improvement of power factor is very important. In this article, we are going to discuss the causes of lagging power factor, the effect of lagging power factor and improvements.


Lagging Power Factor


In an AC Circuit, when current lags behind the voltage with some angle then the lagging power factor occurs.
Here, you can see in the below figure, a pure inductive load is connected with the AC supply. The current lags behind the voltage with a 90-degree angle.

lagging power factor


It is called Zero Lagging Power Factor because the value of the power factor is zero and it lagging in nature.

The current lags behind the voltage means, Voltage will achieve its peak value first, and after some time current will achieve its peak value. In the above wave diagram, you can see this scenario.



Causes of Lagging Power Factor


The main cause of lagging power factor is using Pure Inductive(L) Load or Resistive-Inductive(R-L) Load.

When a pure inductive load(which has no resistance) is connected with AC supply then no active or real power is consumed only reactive power flowing in the circuit and the power factor will be Zero lagging.

When a Resistive-inductive load is connected with AC supply, both active and reactive power is flowing. The power factor will be lagging in nature.

The example of some devices and machines which can cause lagging power factor are Induction motor, transformer, Air conditioner, refrigerator, etc.



Effects of Lagging Power Factor


For Linear Loads, lagging Power Factor creates losses, power waste, etc. For a non-linear load, the lagging power factor creates harmonic noise.

Due to the low power factor especially for lagging power factor, more electrical power will flow in the circuit that's why more current also flows. As more current flow copper loss also increases and reduces the life of the conductor.

Lagging Power Factor creates transient voltage fluctuations in electrical circuits.

Lagging Power Factor increases the operational cost of an electrical transmission and distribution system. Due to Lagging Power Factor, large companies need to pay a penalty with the electric bills.



Lagging Power Factor Improvement


Improvement of power factor means, taking its value near to Unity.
Mostly capacitor bank is used to improve the lagging power factor for large inductive loads.
The capacitor bank is connected in parallel with the load to improve the power factor.

Synchronous Condensor or synchronous motor is also used to improve the lagging power factor because it can take the leading current when its field voltage is varied.


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Lagging Power Factor Causes, Effects, Improvements Lagging Power Factor Causes, Effects, Improvements Reviewed by Author on 1/21/2020 Rating: 5
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