What is Three-Phase Power?

Three-phase electric power is a common method of alternating current electric power generation, transmission, and distribution. It is a type of polyphase system and is the most common method used by electrical grids worldwide to transfer power. It is also used to power large motors and heavy loads because it is more efficient than single-phase power.

How to Calculate Three-Phase Power

To calculate the power in a three-phase system, you typically need the Line-to-Line Voltage (V), the current in Amps (I), and the Power Factor (PF). The fundamental formula for Active Power (P) in a balanced three-phase system is:

P = √3 × V × I × PF

Where √3 (the square root of 3) is approximately 1.732. This factor accounts for the phase relationship between the three different lines.

Key Components Explained

• Active Power (kW): The "real" power used to perform work, such as turning a motor or lighting a bulb.
• Apparent Power (kVA): The total power flowing in the circuit, combining real and reactive components.
• Reactive Power (kVAR): The power that oscillates between source and load, used to maintain magnetic fields.
• Power Factor: The ratio of real power to apparent power, ranging from 0 to 1.

Frequently Asked Questions

Why is √3 used in the formula?

In a balanced three-phase star (Y) or delta connection, the relationship between line-to-line and line-to-neutral values involves the square root of 3 due to the 120-degree phase shift between phases.

Can I use this for 208V and 480V systems?

Yes, this calculator is compatible with any standard three-phase line-to-line voltage including 208V, 400V, 480V, and 600V.