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# 3 phase power

Discuss 3 phase power in the Commercial Electrical Advice area at ElectriciansForums.net

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#### peterpan

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how is 3 phase power 415v when each phase is 230/240v? I know its a stupid question but im not a spaks.

Ta

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#### Skotz

Not a stupid question at all mate. For a full and complete answer do a search on Wikipedia its got a great page on this very topic.

Hope that helps you.

Skotz

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#### Shakey

Basically, imagine a sine wave (like an S on its side). This is the wave form for a single phase

Now take three of these and space them 120 degrees apart. (or one third) This is three phase

Now this is what is at the transformer at the end of the street.

Now imagine these three phases in a star formation with a central point. The central point is the neutral.

Coming into your house is one of the phases and the neutral. Between any of the phases and neutral is 230V. BUT, because each of the phases is 120 degrees apart, YOUR 230V happens at a slightly different time to the 230V off another phase.

Because the phases are at different points at different times, the result is that if you measure BETWEEN any of the phases you will get 400V (415 in old money!)

that's as simple as i can get it without diagrams. And any more and we will have to start hitting some serious formulae

hope this helps

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