Small-Scale Hydroelectric Generator

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Build It!

The Pembina Institute   Important note: Please read and follow these instructions carefully, step by step! Have a one member of your group read each step aloud to be sure the instructions are clearly understood. Do not proceed until each step has been completed.

Tools Electric drill, with ??" drill bit Scissors Electrical tape Ruler 10 cm (3.5 inch ) nail or awl Hot glue gun, with 3 glue sticks White glue Utility knife Pencil sharpener Permanent felt tip marker Magnetic compass Wire cutters Gloves Safety glasses Materials Micro-hydro template sheet (see bottom of page to download) 4L plastic jug (rectangular style, from vinegar, windshield washer fluid, or similar-see illustration) 10 plastic spoons 1 large cork (3.5 to 5 cm) Enameled magnet wire, 24 gage (approx. 100 m) Foamcore or heavyweight corrugated cardboard (approximately 22 cm by 30 cm) 6 mm (1/4 inch) wooden dowel (20 cm long) 4 ceramic or rare earth magnets (18mm or larger) clear vinyl tubing (6 cm long, ??" inside diameter) 4 brass paper fasteners

Safety Precautions Cover the back of the template with a thin, even layer of glue. Use caution when cutting with the utility knife. Prepare the Disks The generator we are building has two basic parts-the rotor and the stator. The stator is the part that remains stationary and has coils of wire to collect electricity. The rotor is the part that moves. It is equipped with powerful magnets that will induce current of electricity in the coils. Glue the template sheet to the cardboard with white glue. Be sure to spread a thin layer of glue evenly over the entire back of the template. When the glue has dried, use the utility knife to cut the rotor and stator disks from the cardboard sheet. Carefully trim the edges. Also, be careful not to damage the tabletop with the utility knife. Work on a piece of scrap wood or a cutting board. Using an awl or sharp nail, punch a small hole through the rotor disk at its exact center, as shown. Using the utility knife, make a larger (1 cm) hole at the center of the stator disk.   The Stator Check to make sure you have good connections between the coils. Prepare a jig for winding your coils by cutting a 3 cm by 16cm piece of cardboard, folding it in half and securing with a small piece of electrical tape. Cut 8 short (4 cm) strips of electrical tape and set these aside. Leaving a lead of about 10 cm, start winding the first coil on the jig. Wrap the wire neatly onto the jig, forming a tight coil. Use 200 wraps or turns. Carefully slip the coil off the jig and secure it using two pieces of the electrical tape you set aside in step 2 above. Using a small patch of emery cloth or sand paper, remove the enamel insulation from the ends of each lead, exposing about 1 cm of bare wire. Be sure the wire is completely bare! Repeat steps 1 through 5 to make three more coils. Lay the coils loosely on the disk in the position shown by the template. Arrange the coils so their windings alternate between clockwise and counterclockwise, as shown on the template. THIS IS VERY IMPORTANT! Arrange and connect the coils so that an electron would follow the path shown by the arrows, starting with the counterclockwise coil on the left hand side. When you are sure you have them arranged correctly, connect the coils by twisting the bared ends together, covering the connections with small pieces of electrical tape. Check your connections: Set your multi-meter for measuring electrical resistance (ohms). If your connections are good, there should be little resistance to the movement of electrons, and the meter should produce a reading of about 10 ohms or less. To check this, touch or connect the probes to the two free ends of the wires from the coils. If the coils are not properly connected, the reading will be a very large number, or infinity. Once you are confident the coils are properly positioned and connected, glue them to the stator disk. Lift each coil up a little and apply a large blob of glue to the template where the coil touches. Let the glue solidify before gluing the next coil. With the utility knife, cut 4 slits through the cardboard between the magnets as shown on the template. These slits will be used to fasten the stator to the plastic container later.   The Rotor Obtain 4 magnets. Using the magnetic compass, determine the polarity of each face, and mark the south pole Checking the polarity of one face of a magnet using a compass. of two magnets and the north pole of the remaining two using a felt pen. Warm up your hot glue gun, and prepare to attach the magnets to the rotor disk. The magnets must be arranged so that their polarity alternates (i.e. N-S-N-S). Their position and polarity are indicated on the template. Squeeze a small (1cm) blob of hot glue on the spot where the first magnet will go. Quickly press a magnet with its washer onto the blob, as shown below. Allow the glue to solidify before moving onto the next magnet. Repeat this for the remaining 3 magnets, making sure to alternate north and south poles as you go.           The Shaft Cut the dowel down to 20cm in length. Using a pencil sharpener put a point on each end of the wooden dowel (it is not necessary to make a sharp point-blunt will do).   The Turbine Drill a ??" (6mm) hole through the CENTER of the large cork, or use a cork borer to make the hole. Center the wide end of the cork on the marking guide on the template page, and mark the cork with a pen or pencil. Place the cork wide-end down on a cutting board. Use the utility knife to cut shallow slits into the cork where the spoons will be inserted. USE CAUTION! Obtain 8 plastic spoons. Using the wire cutters, cut the spoon handles leaving a 1 cm stem on the bowl of the spoon. Be sure the glue gun is warmed up and that you have a glue stick or two handy. Insert the first spoon into the cork, using the turbine template as a guide. Push the stem of the spoon into the cork to a depth of about 1 cm. Repeat step 6 with the remaining 7 spoons. Adjust the angle and depth of the spoons so they are evenly spaced and all project from the cork at the same angle. When you are satisfied with your turbine, add some hot glue to each spoon to secure it on the cork.   The Housing Obtain the plastic container and tear off any labels that might be attached to the sides. Using scissors or a utility knife, cut part of the bottom off, as shown in the photo below. Using a ruler, find the center of the side as accurately as you can. Mark this point with the permanent marker. Repeat for the other side. At the mark on each side of the container, drill a ??" (6mm) hole through the plastic. Lay the stator with its attached coils on the side of the container so that its center hole is over the hole in the container. Push the nail (or awl) through each slit on the stator disk to mark the locations of these slits on the side of the plastic container. Using the utility knife, make 4 small slits on the side of the container, corresponding with those on the stator disk. Using the brass fold-over tabs, securely mount the stator disk to the side of the plastic container. Bend the tabs flat on the inside of the container, as shown.   Final Assembly An expanded view of the micro-hydro turbine. The magnets should be close to, but not touching the coils as they turn. Reinforce the rotor disk with hot glue. With scissors, cut the vinyl tubing into two small lengths, each 1 cm long. Position the turbine inside the container so the spoons face the neck of the bottle. Push the shaft through the turbine's cork. Work the cork and the tubing down the shaft so the shaft comes out the other side of the container and projects by about 4 cm. Ajust the position of the turbine so the spoons line up with the neck of the container. Adjust the position of the tubing so that it comes close to but does not touch the inside of the container. Slide the second section of tubing over the end of the shaft as shown. The two pieces of tubing will help to keep all parts of the turbine positioned correctly when it spins. Spin the shaft to be sure it turns without binding, and that the turbine does not strike the inside of the container as it spins. Slide the rotor disk onto the shaft. Position it so that the magnets come to within 2 or 3 millimetres of the coils. Spin the shaft to be sure the magnets do not strike the coils. Check the rotor disk to see that it spins true. Turn the shaft slowly and note any wobble. Adjust the angle of the disk on the shaft as necessary. When the rotor disk spins without wobbling, fix it in position with hot glue applied to the point where the shaft passes through the reinforcing disks.

Test It! (Click to continue)

Download: Hydroelectric Generator Construction Plans  [PDF Format - 1619 Kb] Micro-hydro Template Sheet  [PDF Format - 74 Kb]