Winter Programming: Physical Electricity
Tonight was a cold night here at Mezzacello Urban Farm. It was 0C outside and the classroom and deck are not ready to use yet. So I decided to teach the All That (Teens Hopeful About Tomorrow) kids their winter programming: physical electricity workshop in the warm, but unfinished kitchen.
This workshop is part of a three-section, nine sessions each partnership between Mezzacello Urban Farm and All That this fall-winter. Each section focuses on a different theme like bioengineering, livestock and farming, and physical electricity. It’s been a blast so far and I can truly see growth and intense interest in the kids, just from their focus and the questions they ask.
The Science, Practicality, and Economics of Wire
Tonight the All That STEAM kids were supposed to be working with the livestock, but the weather was too cold, so we switched to exploring wiring and renewable energy systems. They started by creating a map of Mezzacello and the location of the two turbines that still needed wiring. They did the math and discovered one wire needed to be 47 feet long (14.3m) and another that was 12 feet long (3.64m). Then we learned all about how three-phase AC motors work.
After explaining how the magnets and wires inside an AC motor create electricity as the armature spins, I could start to see recognition of why AC motors have three wires. Then we covered DC and why it is not as useful as AC over long distances and heavy loads. I could tell they understood the difference, and they learned why many appliances have blocks or wall warts on their cords.
Now that they understood that their compound wires needed three wires for EACH wire from the wind turbine, they got down to measuring wire. Watching them navigate a measuring tape and handling stiff wire was fun. It took some imagination (we were in a 25’ long room) but they managed.
Creating a 47’ link was fun. Now they had to create the 47’ long wires in triplicate! Then they set out wrapping them together using electrical tape and eventually they became quite good at it. That long wire is tight.
Note how efficiently the three wires are taped together and how tight that roll of wire is!
How To Make a Three-Phase Wire
I explained that the wires had to be tight so they were thin enough to fit through the metal conduit tube that runs through sheds 1 and 2 and across the poultry run. The rubber insulation of this wire is not rated to stand up to UV radiation, and if they tried to run a three line wire unwrapped through already tightly packed conduit, they were asking for chaos. They managed pretty well.
Unfortunately two of the 47’ wires were cut short. So they decided they would just measure another 47’ long piece of wire. That’s when I explained that each linear foot of solid copper wire was $1.50. They quickly did the math and I could tell they knew why we would NOT be doing that.
After they did the math, ($211 for three lines in one cable and $54 for the three lines in the other) they understood the economics of renewable power. They also learned how to use wire connection crimps to make those 13” short wires 13” longer!
A 60Amp wind turbine MPPT with a dump for excess energy.
Once all the wires were ready, we connected them into the charge controller and power dump control for the wind turbines. I will have my CAHS intern install these in the power shed on Wednesday next. I love it when a plan comes together!
I am really proud of the All That STEAM kids. They were motivated especially when I explained we needed they two turbines online ASAP! One of the rabbits is pregnant and we will need all the energy we can muster to heat those baby rabbits this winter! Good job, All That!
