A low power factor means that the electrical load is not totally utilizing the available electricity i.e flow higher load current than necessary which increases electricity costs and reduces system efficiency. The main cause of low power factor is the inductive load. The current lag by 90° behind the voltage in inductive load causing a large phase difference resulting low power factor.
Effect of Low Power Factor
The effect of low power factor has been listed below.
- Copper loss increases - Copper loss is inversely proportional to the square of power factor i.e as power factor decreases copper loss increases resulting decrease in efficiency of the power system.
- Require larger kva transformer - KVA rating of transformer is inversely proportional to power factor of the system or machine i.e as power factor decreases increases kva rating of transformer increasing size and cost of the transformer.
- Poor voltage regulation - Decrease in power factor increases voltage drop in transformer and alternator resulting poor voltage regulation.
- Low efficiency - Decrease in power factor reduces overall efficiency of the system.
Causes of Low Power Factor
Some of the main causes of low power factor has been listed below.
- Inductive loads - Approximately 90% of industrial loads are inductive that reduces the power factor as current lags by 90° behind the voltage in the case of inductive load causing a large phase difference that increases reactive component of the system resulting lagging or low power factor.
- Harmonic currents - The presence of harmonic currents reduces the power factor of the system.
- Variation in load - The load demand in a power system is not constant throughout the day i.e it varies according to different season and time resulting low power factor.
- Improper wiring - Due to improper wiring or electrical accident, an imbalance in the three phase wiring occurs resulting low power factor.
- Magnetizing current - During low load period, the supply voltage increased which increases the magnetizing current resulting low power factor.
- Long Distribution Lines - Long distribution lines can cause voltage drop and increases the reactive power in the system resulting low power factor.
Sources of Low Power Factor
Some of the main sources of low power factor has been listed below.
- Distribution Transformer
- Incandescent Lamps
- Mercury Vapour Lamps
- Induction Motors
- Under-excited Induction Motors
- Industrial Heating Furnaces
- Welding Transformers
- Arc Lamps
- Solenoid and chocks
Methods of Power Factor Improvement or Correction
Low power factor has several disadvantages as mentioned above in effect of low power factor. So, overall power factor of the power system must be improved using various methods which are listed below.
- Use Capacitor banks
- Use Synchronous Generators
- Use Phase Advancers
- Use PFC (Power Factor Controller)
- Avoid using Machines above Rated Voltage
- Minimize operation or install VFD (Variable Frequency Drive) to lightly loaded induction motors.
- Replace lightly loaded motors with required capacity motors
Conclusion
Hope, you have clearly understand about the low power factor, its effect, causes, sources and methods of power factor improvement or corrections. Make sure to leave your opinion and suggestion about this post in the comment section below.