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Three-phase power
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Three AC waves offset by 120° power industry.
Three AC voltages offset by 120° supply constant power to loads and give efficient motors. Line voltage = √3 × phase voltage.
400 V line in a factory = 230 V phase.
Used for industrial supply.
In more detail
Three-phase power uses three AC voltages offset by 120 degrees, delivering power more smoothly than single-phase. It is used for industrial motors and grid transmission.
Real-world uses
- Factories run large motors on three-phase supplies.
- Power grids transmit three-phase power for efficiency.
- Power grids generate and distribute three-phase electricity, which is efficient for large motors and industrial equipment.
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Frequently asked questions
Why is three-phase better?
It provides constant power for motors and uses less conductor material per unit of power.
What are the lines called?
Usually labelled L1, L2 and L3, with a neutral in star-connected systems.
Why is three-phase used?
The total power delivered is steady rather than pulsing, and three-phase motors are simpler and cheaper to build.
Related topics in AC Circuits & EM Waves
Parallel resonance · Filters · Transformers in power transmission · Rectification and smoothing · Displacement current · EM wave generation