Power factor has been used to measure how efficiently electrical equipment utilizes the amount of power supplied to it. The higher the power factor, the better the equipment's performance. Equipment with low power factor means that power has not been efficiently used and hence power losses occur. Direct current has no power factor because it is accompanied by zero frequency. For alternating current voltages, power factor is a norm and ranges between zero and one, where one is the perfect system, and zero is the bad system.

 

Defining Power Factor

First, note that power factor is a ratio meaning it is unitless. It is a ratio between the energy a device can transmit to the output and the energy it consumes from the input electrical source. It is one of the key figures used by designers of electrical and electronic devices to meet the power requirements and regulations within several countries and other organizations.

In other words, power factor is the ratio between the system’s true power (kW) and its apparent power (kVA):

Power_Factor=True_Factor(kW)Apparent_Power(kVA)

PF=kWkVA

A power factor (PF) of 80% (or 0.8) means that only 80% of the electrical power drawn from the source does useful work, with the remaining 20% being "reactive power" that moves back and forth, causing inefficiencies like increased current flow, higher losses, and potentially higher costs for businesses. It's the ratio of real power (kW) to apparent power (kVA), indicating moderate efficiency, but a lower PF suggests more wasted energy, often due to inductive loads like motors.  

What it means:

• Efficiency: 

  Your electrical system is using power moderately efficiently; 80% of the power delivers work, and 20% doesn't.

• Formula: 

  PF = Real Power (kW) / Apparent Power (kVA).

• Example: 

  If a system uses 100 kW of real power, it draws 125 kVA (100 kW / 0.8 = 125 kVA) from the source, meaning 25 kVA is reactive power.

• Inductive Loads: 

  A PF of 0.8 often results from inductive loads (motors, transformers) where current lags voltage, creating this inefficiency.

Why it matters (Low PF effects):

• Higher Current: Requires heavier current to deliver the same amount of work.

• Increased Losses: Leads to more heat and energy loss in wires.

• Voltage Drops: Can cause voltage sags, affecting equipment performance.

• Utility Penalties: Utilities often penalize large users for low power factors to encourage efficiency.

The Ideal:

• A power factor of 100% (or 1.0) is ideal, meaning all power does useful work (like a purely resistive load).

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