In modern power systems, almost all electrical energy is generated, transmitted, and distributed in the form of AC. Due to the sinusoidal nature of AC, there is a phase angle difference between voltage and current. The cosine of this phase angle is known as the power factor.
What is Power Factor?
Definition:
- The ratio of Active Power (kW) to Apparent Power (kVA).
- Cos(θ) where θ is the angle between voltage and current waveforms.
- The ratio of resistance (R) to impedance (Z).
Power Factor for Different Types of Load
- Resistive Load (e.g., Bulb): Power Factor = 1 (Unity)
- Inductive Load (e.g., Fan, Motor): Power Factor = Lagging
- Capacitive Load (e.g., Capacitor Bank): Power Factor = Leading
Power Triangle
The power triangle helps in understanding the relationship between active, reactive, and apparent power:
Fig: Basic Power Triangle
- OA = Active Power (kW) = VIcosθ
- OB = Apparent Power (kVA) = VI
- AB = Reactive Power (kVAR) = VIsinθ
Fig: Detailed Power Triangle Showing Phase Angle
Disadvantages of Low Power Factor
1. Larger kVA Rating of Equipment
Low power factor leads to an increase in the apparent power demand, which requires larger capacity equipment, increasing cost and size.
Fig: Effect of Power Factor on Apparent Power
2. Larger Conductor Size
Low power factor causes more current to flow for the same amount of real power. Hence, to carry the higher current safely, larger cross-section conductors are needed.
Fig: More Current Requires Larger Conductors
3. Increased Copper Losses (I²R Losses)
Copper loss is directly proportional to the square of the current. Low power factor increases current, thereby increasing I²R losses, reducing system efficiency.
Fig: I²R Losses Increase with Current
Hope this post helped you understand Power Factor clearly. For more such concepts, keep visiting Electrical JE Education.