Power Factor & Correction Methods
Power factor is the ratio of real power used to do work to the apparent power supplied to an electrical circuit. It indicates how effectively electrical power is being converted into useful work. A low power factor means more energy is wasted. Correction methods, such as adding capacitors or synchronous condensers, improve the power factor by reducing the phase difference between voltage and current, leading to increased energy efficiency and reduced losses in electrical systems.
Power Factor & Correction Methods
Power factor is the ratio of real power used to do work to the apparent power supplied to an electrical circuit. It indicates how effectively electrical power is being converted into useful work. A low power factor means more energy is wasted. Correction methods, such as adding capacitors or synchronous condensers, improve the power factor by reducing the phase difference between voltage and current, leading to increased energy efficiency and reduced losses in electrical systems.
💡 Key Takeaways
- Understand what power factor is and why it affects efficiency and energy costs.
- Distinguish between real power (kW), reactive power (kVAR), and apparent power (kVA) and how PF relates to them.
- Recognize leading vs. lagging power factor and typical causes of poor PF in equipment and loads.
- Learn common power factor correction methods (passive/power factor correction using capacitors, reactors, and APFC) and when to apply them.
- Know how utilities charge or credit low power factor and the basics of sizing a correction system for a facility.
❓ Frequently Asked Questions
What is power factor?
The ratio of real power (kW) to apparent power (kVA). It equals cos(phi) and indicates how effectively current is used. A higher PF (closer to 1) means more efficient power use.
What causes a low power factor?
Inductive loads (motors, transformers) draw reactive power, causing current to lag voltage. Capacitive or non-linear loads can cause a leading PF and distortion.
Why should you improve power factor?
Improving PF reduces current for the same real power, lowers conductor losses, frees capacity, and can reduce utility penalties and improve voltage regulation.
What are common methods of power factor correction?
Passive correction with capacitors (and sometimes reactors) near loads; detuning to avoid resonance; Active Power Factor Correction (APFC) using power electronics; synchronous condensers.
What is the relationship between kW, kVAR, and kVA?
kW is real power, kVAR is reactive power, kVA is apparent power. PF = kW / kVA = cos(phi); reactive power can be lagging (inductive) or leading (capacitive).