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Electrical & Electronics Engineering vocabulary · Power Systems and Electrical Machines

Three-phase

Meaning in electrical & electronics engineering, with examples

/ˌθri ˈfeɪz/adjectiveCore term

In electrical & electronics engineering, three-phase means: Describing an AC system with three voltages of the same frequency, each shifted by 120 degrees from the others. It is used to transmit power and run large motors efficiently.

In Turkish: üç fazlı, trifaze

How it is used

Used before nouns: three-phase supply, three-phase motor, three-phase power. In Turkey and Europe a low-voltage three-phase supply is 400 V between phases and 230 V from phase to neutral. The opposite is single-phase, which most homes use.

Example sentences

  1. The compressor needs a three-phase supply, so we can't plug it into a normal socket.

  2. Check that the three-phase motor turns in the right direction before you couple it to the pump.

Common collocations

  • three-phase supply
  • three-phase motor
  • three-phase power
  • three-phase system
  • single-phase
  • phaseOne of the live conductors in an AC system, such as L1, L2 or L3 in a three-phase supply. It also means the timing position of a waveform, measured in degrees.
  • neutralThe conductor that carries current back to the source in an AC system and is normally close to earth potential. In IEC wiring it is blue; in North America it is white.
  • motorA machine that converts electrical energy into mechanical rotation. Most industrial machines use three-phase induction motors, while small devices often use DC or brushless motors.
  • loadAny device or circuit that draws power from a source, such as a motor, a lamp or a heater. The word also means the amount of power or current being drawn.
  • transformerA device that transfers AC power from one winding to another through a shared magnetic core, usually to step the voltage up or down. It does not work with DC.

More terms: Power Systems and Electrical Machines

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