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In the previous part, we discussed some of the reasons behind the low magnitude of the power factor. In this part, we will look at some of the equipment and techniques which we can employ to improve the power factor.
We already know that inductive loads decrease the power factor by consuming reactive power from the system. But what if we were to insert something in the system which would act as a secondary source of reactive power. This course of action would cancel out the reactive power needs of the inductive loads. The phase angle between the apparent and active power will decrease, which would improve the overall power factor.
Power factor correction equipment includes include capacitors, synchronous condensers and AC exciters.
Keep in mind, that the reactive power required by the inductive loads is lagging in nature whereas the reactive power supplied by the correction equipment is leading in nature.
First up, we have the static capacitors which are the simplest form of power factor correction still in use today. This method consists of inserting a capacitor bank in parallel with the incoming terminals of the inductive load.
Once inserted, the reactive power by the inductive load is supplied by the capacitor bank which neutralizes the effect and improves the power factor magnitude. This is because the reactive power required by the inductive loads acts at a positive 90 degrees angle to the real power, and the capacitor acts at a negative 90 degrees angle to the real power. Therefore, they cancel each other out reducing the phase angle.
We will be solving a practical example in the next part where we will calculate the parameters of the power factor correction capacitor.
For now, let’s focus on the other two methods of power factor correction. The next one is called a synchronous condenser.
We already know from previous parts, that motors have lagging power factors and they consume reactive power. But what if we were to provide it with additional magnetic flux than necessary. And in addition to that, we remove any load attached to its shaft.
The additional magnetic flux would then cause the motor to start supplying reactive power instead of consuming it as was the case originally. This synchronous motor starts to behave like a capacitor and it draws the reactive current from the system, thereby improving the overall power factor.
A third way to improve the power factor is to use a phase advancer. Since inductive loads like the induction motor operate by drawing reactive current from the system. What if we provide it with another source to provide the required reactive current? This is where a phase advancer comes into play. It provides the required excitation current for the motor which relieves the system of any reactive power requirements, thus improving the power factor.
To summarize it all, there are multiple ways to achieve power factor correction, and it is generally recommended to keep the power factor above 0.8 in order to lower utility costs, minimize system losses and improve the overall system efficiency.
In part 4, we will solve a practical example using mathematical calculations employing the capacitor bank correction technique.
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