How Do Three-Phase Transformers Work?


Three-Phase Power

  • A three-phase transformer is an electrical device that works with three-phase power. The power that is supplied to every home is single-phase power, because the voltage swings from high to low 60 times a second, or 60 Hertz. There are two or three metal prongs on a typical American electrical cord. The flat tabs are for hot (where the voltage is) and neutral, where the optional round plug is for the ground.

    The three-phase power plug will have three or four metal prongs. In the case of three, each prong will represent a live voltage line. The fourth may be a neutral line. The real benefit to three phases is that the power along all three live voltage lines will be constant. Plus, the swinging of each line will result in a perfect balance, which is more efficient and easier on the electronics.


  • As is the case in any power transmission scheme, a transformer is needed to convert from high voltages to low voltages. The higher voltage has a lower current, and less energy is wasted along the path from power plant to wall plug. Devices cannot handle this strong a voltage, so the transformer steps in to make it manageable. The three phase transformer is no different. It will convert high voltage, three phase power into lower voltage, usable three-phase voltage.

How It Is Made

  • The three-phase transformer can be built in two different ways. First, each of the three voltage lines can have a single-phase transformer. These are similar to the large gray cylinders on the top of utility poles. Each voltage line goes through a transformer where each is independently altered. The other kind is where the three single phase transformers are combined into a single, three-phase transformer. This three phase transformer is more complicated but ensures that all three lines are treated identically.

Related Searches

  • Photo Credit Wikimedia Commons
Promoted By Zergnet


Related Searches

Check It Out

22 DIY Ways to Update Your Home on a Small Budget

Is DIY in your DNA? Become part of our maker community.
Submit Your Work!