Sometimes we build to innovate, and sometimes we build just to have the satisfaction of saying we made it ourselves. Yet there is another reason to construct something ourselves: To learn, just as [Fraens] has done with this 3D-printed generator. (Video, embedded below.)
[Fraens] starts off with a jig for winding the individual coils, but then the jig itself snaps into a the stator ring. The stator ring is sandwiched by two rotors which rotate on a brass shaft suspended by needle bearings. With the exception of the hardware, all the structural parts are 3d printed.
What really separates the generator build isn’t how it’s built, but rather how [Fraens] has put it to use as tool for learning and experimentation. By plotting input torque vs electrical output, [Fraens] is able to calculate efficiencies in multiple configurations, and has some interesting conclusions to share toward the end of the video. We appreciate how the documentation and analysis help iterate the design towards higher efficiency and will inform the next build.
What kind of power service is in the United States? You probably answered 120-volt service. If you thought a little harder, you might remember that you have some 240-volt outlets and that some industrial service is three phase. There used to be DC service, but that was a long time ago. That’s about it, right? Turns out, no. There are a very few parts of the United States that have two-phase power. In addition, DC didn’t die as quickly as you might think. Why? It all boils down to history and technological inertia.
You probably have quite a few 120-volt power jacks in sight. It is pretty hard to find a residence or commercial building these days that doesn’t have these outlets. If you have a heavy duty electric appliance, you may have a 240-volt plug, too. For home service, the power company supplies 240 V from a center tapped transformer. Your 120V outlets go from one side to the center, while your 240V outlets go to both sides. This is split phase service.
Industrial customers, on the other hand, are likely to get three-phase service. With three-phase, there are three wires, each carrying the line voltage but out of phase with each other. This allows smaller conductors to carry more power and simplifies motor designs. So why are there still a few pockets of two-phase?