AC Generation

How a Waveform Is Generated

AC generation with an alternator

If Faraday has taught us anything it is this:  Any time you pass a conductor through a magnetic field, you induce a voltage.  If we take that conductor and turn it into a loop and spin it continually through that magnetic field, we have created an alternator.

Figure 50. Alternator picture

This means that a voltage will constantly be induced.  However, this is not a flat line voltage like direct current.  It creates an oscillating voltage that rises and falls.

Is this what you mean by sine wave generation?

Yup, this is exactly what I mean.  As the conductor spins through the field, there will be times that it does not cut any lines of flux.  There will be times when it cuts some of the lines of flux, and there will be times that it is cutting the maximum amount of flux lines that it can.  This means that at some point during the sine wave generation there will be no voltage generated.  Then there will be some voltage generated, and then there will be a maximum voltage generated.  This creates this thing of beauty.  A sine wave.

Figure 51. Sine wave

Oh yeah, I think I have seen that before

This wave pattern occurs often in nature, including ocean waves, sound waves and light waves.  In fact, if you take the hours of daylight in a day and graph it out with the months of the year, guess what?  A sine wave is generated.  If you’d like to read an interesting article on the seasons and sine wave generation, read Calculus of the seasons.  Isn’t nature cool?  But I digress.  This sine wave is extremely important when it comes to electrical generation.  Future postings will discuss its importance and go into in-depth analysis of the waveform.


This video explains how a sine wave is generated in an alternator.

Sounds like fun

Oh, it’s fun all right.  Trust me.  If you find this stuff interesting, it becomes a lot easier to learn and understand.  (Fatherly lecture over).  If you have a foundational understanding of this concept, then single phase and three-phase generation should be a snap.


Sine wave generation. video by The Electric Academy is under a Creative Commons Attribution Licence.

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