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Technical Terms

In an AC power system, the power factor is the ratio of real power consumed by the load to the apparent power flowing in the circuit. It is a measure of how effectively electrical power is utilized.

How to Calculate Power Factor Calculating power factor is based on the ratio of working power (also known as active power) to the apparent power. In practical electrical engineering, this is expressed using the units of kilowatts (kW) and kilovolt-amperes (kVA):

Power factor | Technical Terms: Power Supplies | Matsusada Precision

This PF (kW/kVA) calculation allows engineers to determine exactly how much of the supplied current is performing actual work.

When devices such as motors operate, the real power consumed is often less than the apparent power. This occurs due to the nature of the load:

  • Inductive loads (such as coils or motors) cause the current to lag behind the voltage, resulting in a lagging power factor.
  • Capacitive loads cause the current to lead the voltage, resulting in a leading power factor.
These components generate reactive power, which oscillates between the load and the AC source without being consumed, thereby reducing the overall power factor.

In other words, a higher power factor indicates a more efficient use of electrical power. The power factor can be measured using a power factor meter or similar devices. In an ordinary household, the power factor is typically around 85%, while in facilities with high-voltage power receiving equipment (such as electrical substations or switchgear), it is typically maintained in the range of 90% to 99%.

Improving Power Factor The ideal goal for any electrical system is to achieve unity power factor (PF = 1.0), where the active power equals the apparent power, ensuring maximum efficiency.
To correct poor power factor and improve power factor in industrial environments, power factor correction is employed. This is typically achieved by installing capacitors to neutralize the effects of inductive loads, reducing the strain on the electrical infrastructure and lowering energy costs.

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