Power factor is a measure of how efficiently electrical power is used in an AC (alternating current) power system. It represents the ratio of the real power (active power) to the apparent power in the system and is expressed as a decimal or a percentage.
In an AC circuit, there are two types of power: real power (P) and reactive power (Q). Real power is the actual power that is consumed and does useful work, such as powering motors, heating elements, or lighting. Reactive power is the power that flows back and forth between the source and inductive or capacitive loads (such as transformers, motors, and capacitors) without performing any useful work. It only helps establish magnetic fields or store energy temporarily.
The formula for calculating power factor (PF) is:
Power Factor (PF) = Real Power (P) / Apparent Power (S)
Where:
Real Power (P) is measured in watts (W).
Apparent Power (S) is measured in volt-amperes (VA).
Significance of Power Factor in AC power systems:
Efficiency: A higher power factor indicates better efficiency in the utilization of electrical power. A low power factor means that a significant portion of the power supplied is not utilized efficiently but instead contributes to reactive power losses.
Energy Costs: Many utility companies penalize consumers for having a low power factor since it increases the load on the power distribution system. In such cases, improving the power factor can lead to cost savings by reducing penalties on the electricity bill.
Equipment Performance: Some electrical equipment, like motors, work more efficiently with a higher power factor. Low power factors can cause motors to draw more current and overheat, leading to reduced equipment life and increased maintenance costs.
Voltage Drop: A low power factor can result in higher voltage drop in the distribution system, affecting the performance of other connected electrical devices and potentially causing equipment malfunction.
Power System Capacity: A low power factor increases the apparent power in the system, requiring the power generation and distribution infrastructure to handle higher current levels than necessary. This can lead to inefficient use of resources and increased infrastructure costs.
To improve power factor, power factor correction techniques are used, such as adding power factor correction capacitors or using power factor correction equipment. These methods reduce the amount of reactive power drawn from the system, thereby improving the power factor and overall efficiency of the AC power system.