Power factor and its importance

It is the cosine of the phase angle between the applied voltage and resulting current of the circuit

1. Power Factor and its Importance Introduction ( KW, KVAR, KVA) Definition – Power factor Power factor correction Importance of Power factor

2. Introduction ( KW, KVAR, KVA) To understand power factor, we’ll first start with the definition of some basic terms: KW is Working Power (also called Actual Power or Active Power or Real Power). It is the power that actually powers the equipment and performs useful work. KVAR is Reactive Power. It is the power that magnetic equipment (transformer, motor and relay) needs to produce the magnetizing flux. KVA is Apparent Power. It is the “vectorial summation” of KVAR and KW.

3. Definition - 1 It is the cosine of the phase angle between the applied voltage and resulting current of the circuit

4. Definition - 2 It is defined as the ratio of resistance of the circuit to the impedance of the circuit. For a purely resistive AC circuit, R=Z and the power factor = 1.

5. Definition – 3 Power Factor (P.F.) is the ratio of Active Power to Apparent Power . P.F. = KW / KVA P.F. = KW / KW + KVAR

6. What Causes Low Power Factor? Since power factor is defined as the ratio of KW to KVA, we see that low power factor results when KW is small in relation to KVA . What causes a large KVAR in a system? The answer is…inductive loads . These inductive loads constitute a major portion of the power consumed in industrial complexes. Reactive power (KVAR) required by inductive loads increases the amount of apparent power (KVA) in your distribution system. This increase in reactive and apparent power results in a larger angle θ (measured between KW and KVA). A s θ increases, cosine θ (or power factor) decreases.

7. Why Should I Improve My Power Factor? Some of the benefits of improving our power factor include: Lower utility fees Increased system capacity and reduced system losses in your electrical system Increased voltage level in your electrical system and cooler, more efficient motors

8. Power Factor Correction (1) We have seen that sources of Reactive Power (inductive loads) decrease power factor . Similarly, consumers of Reactive Power increase power factor . Thus, it comes as no surprise that one way to increase power factor is to add capacitors to the system. This--and other ways of increasing power factor--are listed in the next slides:

9. Power Factor Correction (2) 1. Installing capacitors (KVAR Generators) Installing capacitors decreases the magnitude of reactive power (KVAR or foam), thus increasing your power factor. Here is how it works (Figure 5)… Reactive power (KVARS), caused by inductive loads, always acts at a 90-degree angle to working power (KW). Inductance and capacitance react 180 degrees to each other. Capacitors store KVARS and release energy opposing the reactive energy caused by the inductor. The presence of both a capacitor and inductor in the same circuit results in the continuous alternating transfer of energy between the two. Thus, when the circuit is balanced, all the energy released by the inductor is absorbed by the capacitor.

10. Power Factor Correction (3) 2. Minimizing operation of idling or lightly loaded motors. We already talked about the fact that low power factor is caused by the presence of induction motors. But, more specifically, low power factor is caused by running induction motors lightly loaded. 3. Avoiding operation of equipment above its rated voltage. 4. Replacing standard motors as they burn out with energy-efficient motors. Even with energy-efficient motors, power factor is significantly affected by variations in load. A motor must be operated near its rated load in order to realize the benefits of a high power factor design.

11. Importance of Power Factor A power factor of one or "unity power factor" is the goal of any electric utility company since if the power factor is less than one, they have to supply more current to the user for a given amount of power use. In so doing, they incur more line losses. They also must have larger capacity equipment in place than would be otherwise necessary. As a result, an industrial facility will be charged a penalty if its power factor is much different from 1.

12. Importance of Power Factor Industrial facilities tend to have a "lagging power factor", where the current lags the voltage (like an inductor). This is primarily the result of having a lot of electric induction motors - the windings of motors act as inductors as seen by the power supply.  Capacitors  have the opposite effect and can compensate for the inductive motor windings. Some industrial sites will have large banks of capacitors strictly for the purpose of correcting the power factor back toward one to save on utility company charges.

13. Prepared by :- Name – Priyansh J. Thakar ID. No. – 16BECEG082 Branch – Computer Batch – CE2 : A