Activity Assembling The Threephase Ac Alternator

The three-phase AC alternator kit is used to generate the AC voltage for the half wave and full wave rectifier circuits. While we could have supplied you with a simple wall transformer that converts 110 VAC to a much lower voltage like 10 VAC, that would not have been as much fun. Instead, we chose to supply you with a miniature wind-powered AC alternator that will be both fun to build as well as fun to use. Plus, you will use it in the next experiment to demonstrate how three-phase power is generated.

Parts Required

(1) Stator (thick disk with embedded wires, may be black or white)

(1) Rotor (black disk with magnets)

(3) Rotor Blades

(2) Triangular hubs

(1) 8" threaded rod, %" diameter (1) Jam nut (thin nut)

(2) Spacer washers (1) Split lock washer (1) Acorn nut

(15) 3/8" pan head Phillips screws

(4) Vinyl self-stick feet

Tools Required

Parallax Screwdriver

7/16" wrench (not included)

WD-40 or other lubricating material (not included)

CAUTION: POWERFUL MAGNETS!

Before building the three-phase AC alternator you must be made aware of the potential damaging effects of the powerful neodymium magnets used in the rotor section. While small in size these six magnets can be dangerous to your fingers, your heart and your computer. So here are some common sense rules to follow when constructing the three-phase AC alternator.

Don't allow the magnets to come in contact with any other ferrous metal like iron, steel or copper. The magnets will immediately bind to the metal with the result being possible pinched fingers. Also, the magnetic hold may be powerful enough to tear the magnets from the round rotor disk when you try to separate them from the metal object.

Don't allow the magnets or, for that matter the entire three-phase AC alternator, near your computer or computer disks, since there is the distinct possibility of erasing the data on the disks. This is particularly true for your computer's hard drive where the bulk of your programs are stored.

Don't let anyone with a heart pacemaker near the three-phase alternator. The magnets can certainly interfere with a pacemaker's function.

The three-phase AC alternator is composed of a stator with the protruding six-conductor cable, a round rotor disk with six magnets, a three-bladed wind turbine and a section of %" threaded rod along with some washers and nuts to hold everything together. Here's how to build it.

Referring to Figure 5-4 and using 4 of the 12 3/8" Pan Head Phillips screws, begin the turbine blade assembly by attaching both triangular hubs on the opposite ends of a single blade.

Make sure that both triangular hubs are mounted with the washer ends facing away from the interior of the blade assembly. DO NOT tighten the screws yet.

Figure 5-4

Attaching the First Blade of the Wind Turbine

Figure 5-4

Attaching the First Blade of the Wind Turbine

V Referring to Figure 5-5, attach the other two blades in the same way, squaring up the blades with the triangular hubs and tightening all twelve screws so that the three blades fit securely to the two triangular hubs.

V Make sure that the blades are squarely aligned with the hubs; this may require un-tightening some screws and then re-tightening them until the blades are correctly aligned.

V Referring to Figure 5-6, attach the completed blade assembly to the nonmagnet side of the rotor disk with the remaining 3 screws by inserting each screw through a hole in the magnet side of the rotor disk and then into a corresponding hole on the triangular hub.

V Try not to allow the screws or screwdriver to attach itself to the magnets (but perhaps it is unavoidable).

V Now tighten the screws so that the rotor disk attaches firmly to the blade assembly.

Figure 5-6

Assembled Wind Turbine and Rotor

Figure 5-6

Assembled Wind Turbine and Rotor

V Referring to Figure 5-7, screw the jam nut (the thinner nut) to one end of the threaded rod, making sure that it fits "flush" with the end of the rod itself.

V Next, insert the %" split lock washer on top of the jam nut, and then insert the free end of the threaded rod through the bottom (non-wire) side of the stator.

Figure 5-7

Threaded Rod Assembly #1

V Referring to Figure 5-8, on the wire side of the stator, screw the %" hex nut (the thicker nut) all the way down the long part of the threaded rod.

V Tighten the bottom (jam) nut with the wrench so the threaded rod is securely in place. Next, drop one (1) spacer washer down the long length of threaded rod so that it sits on top of the hex nut.

Figure 5-8

Threaded Rod Assembly #2

Figure 5-8

Threaded Rod Assembly #2

V As shown in Figure 5-9, slip the blade assembly over the threaded rod being careful not to have the magnets attach themselves to the rod. If they do, carefully detach the magnet rotor so as not to pull any of the magnets off the rotor disk.

V Finally, attach the acorn nut to the top of the threaded rod; finger tight on the acorn nut will be fine.

Figure 5-9

Assembled Wind Turbine three-phase AC Alternator Assembly

Figure 5-9

Assembled Wind Turbine three-phase AC Alternator Assembly

What if my turbine is a mirror image of this turbine? It is possible to assemble the turbine to rotate in a clockwise or counterclockwise direction. In this book, we are using a turbine that rotates counterclockwise. If you assembled yours to turn clockwise, some of your graphs may display a sequence backwards from those shown in the plots in this book.

V As shown in Figure 5-10, attach four rubber feet to the bottom of the stator so that the stator sits level on a flat surface. If the assembly wobbles, then make sure that the jam nut on the bottom side of the stator assembly is flush with the threaded rod. Release and retighten, if necessary.

Figure 5-10

Attach the Rubber Feet

Now set the unit upright and give the turbine blades a spin. The blades should spin freely on the threaded rod, and the magnets should be rotating about a 1/16" to 1/8" above the stator.

If you hear any scraping noise, check the separation between the rotor magnets and the stator to make sure the proper gap is present. You may need to add another spacer washer on top of the one now there.

If you need to reduce the "clatter" of the blade assembly against the threaded rod, attach a piece of transparent tape around the threaded rod where the triangular hub's bushing touches it - both top and bottom. The tape will act as a bearing to make the blade assembly rotate smoother and quieter. However, make sure not to use too much tape; otherwise the blade assembly will drag against it.

Figure 5-11

Adding

Transparent Tape to Reduce Clattering

Figure 5-11

Adding

Transparent Tape to Reduce Clattering

Renewable Energy Eco Friendly

Renewable Energy Eco Friendly

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable.

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