Connecting to 3 Phase Alternating Current
On the page on synchronous generators we mention that each of the electromagnets in the stator is connected to its own phase. You may wonder how that can be done, because in a three phase system we usually have only three conductors (wires). The answer is given in the pictures above:
Delta Connection
If we call the three phase conductors L1, L2 and L3, then you connect the first magnet to L1 and L2, the second one to L2 and L3, and the third one to L3 and L1.
This type of connection is called a delta connection, because you may arrange the conductors in a delta shape (a triangle). There will be a voltage difference between each pair of phases which in itself is an alternating current. The voltage difference between each pair of phases will be larger than the voltage we defined on the previous page, in fact it will always be 1.732 times that voltage (1.732 is the square root of 3).
Star Connection
There is another way you may connect to a three phase grid, however:
You may also connect one end of each of the three magnet coils to its own phase, and then connect the other end to a common junction for all three phases. This may look surprising, but consider that the sum of the three phases is always zero, and you'll realise that this is indeed possible.
© Copyright 1997-2003 Danish Wind Industry Association
Updated 19 September 2003
http://www.windpower.org/en/stat/unitac3c.htm
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