Fator de Potência / Correção do FP

Summary

This video explains the concepts of active, reactive, and apparent power in electrical systems, using a triangle of powers to illustrate the relationships between these different types of power. It covers the importance of power factor correction, why it's needed, and how to calculate the power factor and the corresponding reactive power required for correction. Through practical examples, the script demonstrates how to calculate the apparent and reactive power and how to improve the power factor to avoid penalties, specifically in industrial settings where large inductive loads are common.

Takeaways

• 😀 Power factor (PF) is the ratio of active power (P) to apparent power (S), and it indicates the efficiency of electrical power usage in a system.
• 😀 A low power factor results in higher losses and penalties for industrial facilities due to inefficient use of electricity.
• 😀 The formula for power factor is PF = P / S, and for an ideal system, the power factor should be as close to 1 as possible.
• 😀 A power factor below the minimum threshold (e.g., 0.92 in Brazil) can incur significant penalties from electricity providers.
• 😀 The power triangle illustrates the relationship between active power (P), reactive power (Q), and apparent power (S), where S is the hypotenuse.
• 😀 Reactive power is divided into two types: inductive (lagging) and capacitive (leading), with inductive reactive power being the common issue in industrial settings.
• 😀 To correct a low power factor, capacitor banks are installed to inject capacitive reactive power and balance out the inductive reactive power.
• 😀 The process of calculating the apparent power and reactive power uses Pythagoras' theorem and the relationship between active power (P), apparent power (S), and reactive power (Q).
• 😀 In the example provided, a factory with 75 kW of active power and a power factor of 0.82 needs to correct its power factor to 0.92 to avoid penalties.
• 😀 The required capacitive reactive power for power factor correction is the difference between the reactive power before and after correction, calculated as 20.4 kVAR in the example.

Q & A

What is the significance of the power factor in electrical systems?

The power factor indicates the efficiency with which electrical power is being used. A low power factor means that more reactive power is being consumed, which leads to higher energy losses and may result in fines from utility companies.

How is the apparent power (S) calculated in the given example?

Apparent power (S) is calculated by dividing the active power (P) by the power factor (PF). In the example, with 75 kW of active power and a PF of 0.82, the apparent power is: S = 75 / 0.82 = 91.46 kVA.

What does a low power factor of 0.82 mean for the factory?

A low power factor of 0.82 indicates that the factory is consuming a significant amount of reactive power, which can lead to increased costs and potentially trigger penalties from the utility company for not maintaining an optimal power factor.

How can the factory avoid fines related to low power factor?

The factory can avoid fines by improving its power factor. In the example, correcting the power factor to a minimum value of 0.92 would eliminate the risk of penalties.

What is the corrected apparent power (S) after improving the power factor to 0.92?

After improving the power factor to 0.92, the corrected apparent power (S) is calculated as: S = 75 / 0.92 = 81.52 kVA.

How is the reactive power (Q) calculated in the script?

Reactive power (Q) is calculated using the formula: Q = √(S² - P²), where S is the apparent power and P is the active power. In the example, the initial reactive power with a power factor of 0.82 is 52.25 kVAR, and the corrected reactive power is 31.09 kVAR.

What is the purpose of installing a capacitor bank in the factory?

The purpose of installing a capacitor bank is to supply the necessary reactive power to correct the factory's power factor. In this case, the capacitor bank provides 20.4 kVAR to raise the power factor from 0.82 to 0.92.

What formula is used to calculate the reactive power (Q) after power factor correction?

The formula to calculate the reactive power (Q) after power factor correction is: Q = √(S_corr² - P²), where S_corr is the corrected apparent power and P is the active power. The new value of Q after correction is 31.09 kVAR.

Why does the factory need to correct its power factor to 0.92 specifically?

The factory needs to correct its power factor to 0.92 to meet the minimum requirement set by the utility company. In many regions, a power factor below 0.92 may incur additional charges or penalties for excessive reactive power consumption.

What is the final reactive power (Q) difference that needs to be supplied by the capacitor bank?

The final difference in reactive power, which must be supplied by the capacitor bank, is 20.4 kVAR. This difference is calculated by subtracting the corrected reactive power (31.09 kVAR) from the initial reactive power (52.25 kVAR).