What is a power factor, and how is it improved?

Short Answer:

Power factor is the ratio of real power used by a load to the apparent power supplied from the source. It indicates how effectively electrical power is being used. A high power factor means efficient use of electricity, while a low power factor causes more losses.

Power factor can be improved by adding capacitors or synchronous condensers to offset reactive power, reducing losses, improving voltage, and lowering electricity costs.

Detailed Explanation:

Power factor and its improvement

Introduction

Power factor (PF) is an important parameter in electrical systems that measures the efficiency of power usage. It is defined as the ratio of active (real) power to apparent power in an AC circuit. Power factor values range from 0 to 1, with values closer to 1 indicating better efficiency.

Understanding Power Factor

  • Real Power (P): Power that actually performs work, measured in watts (W).
  • Reactive Power (Q): Power that oscillates between source and load, does no real work but sustains magnetic and electric fields, measured in volt-amperes reactive (VAR).
  • Apparent Power (S): Combination of real and reactive power, measured in volt-amperes (VA).
  • Power factor formula:

PF=PS=cos⁡ϕPF = \frac{P}{S} = \cos \phiPF=SP​=cosϕ

where ϕ\phiϕ is the phase angle between current and voltage.

Causes of Low Power Factor

  • Inductive loads such as motors, transformers, and fluorescent lighting cause current to lag voltage.
  • This lagging current increases reactive power, reducing power factor.

Importance of Improving Power Factor

  • Reduces energy losses in cables and transformers.
  • Increases system capacity to deliver power.
  • Lowers electricity bills due to reduced demand charges.
  • Enhances voltage stability and system reliability.

Methods to Improve Power Factor

  1. Capacitor Banks
    • Capacitors provide leading reactive power, canceling lagging reactive power from inductive loads.
    • Installed near inductive loads or at distribution points.
  2. Synchronous Condensers
    • Over-excited synchronous motors that supply reactive power.
    • Adjustable and help stabilize voltage.
  3. Phase Advancers
    • Used with induction motors to improve power factor by supplying excitation current.
  4. Use of High-Efficiency Equipment
    • Selecting motors and devices designed for high power factor operation.
  5. Load Management
    • Balancing and reducing unnecessary reactive loads.

Benefits of Power Factor Correction

  • Reduced electricity costs.
  • Lower losses and improved equipment life.
  • Better utilization of electrical infrastructure.
Conclusion

Power factor measures how effectively electrical power is used and is improved mainly by compensating reactive power through capacitors, synchronous condensers, and other methods. Enhancing power factor reduces losses, improves voltage, and leads to more efficient and cost-effective power system operation.