Power Factor

Electronic equipment like PCs, monitors, servers, and photocopiers—which are often powered by switched mode power supply (SMPS)—are becoming more and more common in business, industrial, retail, and even residential spaces nowadays. These can create nonlinear loads that force harmonic currents and perhaps voltages onto the main power network if they are not correctly built. This network's equipment and cabling, as well as other connected equipment, are susceptible to harmonic damage. High voltages and circulating currents, equipment malfunctions and component failures, the possibility of overheating and fire, and other potential outcomes are among the issues. If a nonlinear load has a low power factor, it may produce these harmonics. Poor power factors from other loads can exist without producing harmonics.

Table of Contents

• Definition of Power Factor?
• Understanding the Power Factor
• Importance of Power Factor
• Poor Power Factor
• Improving the power factor saves money
• Conclusion

Definition of Power Factor?

The power factor is an indicator of energy efficiency. The more efficiently power is used, the lower the percentage, which is how it is typically expressed.

The ratio of apparent power, expressed in kilovolt amperes (kVA), to working power, expressed in kilowatts (kW), is known as the power factor (PF). Apparent power, also known as demand, measures the amount of power needed to run machinery and equipment over a given time period. By multiplying voltage (V) by current (A), it can be found. The outcome is given in kVA units.

V x A = kVA

Compared to a 75% power factor, a 96% power factor shows greater efficiency. In many areas, PF below 95% is seen as inefficient.

Understanding the Power Factor

The power that actually drives the machinery and enables it to do beneficial, productive work is known as real power (kW). Other names for it include working power, active power, and actual power.

The power needed by some devices (such as transformers and motors) to create a magnetic field so that actual work can be done is known as reactive power (kVAr). Although this equipment has to be energized, it doesn't do any useful job. The total power delivered through the mains that is needed to provide the necessary quantity of real power for the load is known as apparent power (kVA), which is the vector sum of real power (kW) and reactive power (kVAR). "Demand" is another name for it.

Understanding the Power Factor
Image used courtesy of Fuseco

To gain a better understanding of these phrases, let's examine a straightforward illustration. Suppose you have placed an order for a glass of your preferred soft drink. Real Power (kW) is a representation of the drinkable, thirst-quenching part of your drink. Unfortunately, reactive power (kVAR), which is symbolized by a small amount of foam that doesn't satisfy your thirst, comes with your ale. The thirst-quenching drink (kW) and the foam (kVAr) add up to the total contents of your glass (kVA).

Importance of Power Factor

In an AC circuit, power factor is vital because if it is less than 1, the wire must carry more current than if there were no reactance to provide the resistive load with the same amount of (real) power. The circuit is currently dissipating 119.365 watts with the same amount of current, but if our prior example circuit had been entirely resistive, we could have delivered a full 169.256 watts to the load using the same 1.410 amps of current.

Poor Power Factor

To counteract the effects of the load's inductive reactance, one can paradoxically improve a poor power factor by adding another load to the circuit that draws an equal and opposite amount of reactive power. We must add a capacitor in parallel to our example circuit to serve as the additional load, because inductive reactance can only be countered by capacitive reactance. When these two opposing reactances are connected in parallel, the circuit's total impedance equals its total resistance, which brings the impedance phase angle to zero or nearly so.

Improving the power factor saves money

The manner in which electricity utilities and retailers bill you is changing. Actually, customers are required by network regulations to maintain a minimum power factor (numbers vary by location). When a customer's power factor falls below a certain threshold, utility companies may impose a penalty (surcharge) on top of their consumption rates. A low power factor can lead to power losses and voltage drops, which can cause motors and other equipment to overheat and fail. Installing power factor correction equipment can help you lower the current electrical demand on your system and improve efficiency, which may prevent the need for costly infrastructure upgrades if your electrical system is nearly at its limit. Payback durations for power factor adjustments typically range from one and a half to three years. By lowering monthly demand and capacity charges, increasing your power factor can cut your electricity costs. It can be a highly good investment, considering the possible savings and the lifespan of power factor correction equipment.

Conclusion

The ratio of the perceived power supplied to a circuit to the actual power used in the circuit is known as the power factor. Typically, the network's overall power demand exceeds its actual power. Your power factor, which ranges from 0 to 1, is the ratio of your real power to total power. The higher the power factor, the more efficient your site is at utilizing the supplied power. Lastly, because a low power factor necessitates a larger current to supply loads, it raises the total cost of a power distribution system. By purchasing power quality analyzers and putting power factor correction procedures in place, businesses can significantly decrease costs and improve the efficiency of their electrical systems, which will result in cheaper utility bills and less stress on the electrical infrastructure.