Hand Cranked Generator

I have had several people ask about building a generator students can turn by hand. I am putting a short explanation and several pictures on my blog. We built one using an ECM motor minus the module.

It puts out 3 phase AC. It is regulated only by the speed of the person turning it: you would not want to run your computer on it. To get enough speed we used a 12 inch pulley for the students to turn and a 1 inch pulley on the motor shaft: This produces 12 spins of the generator for every one revolution of the hand crank. I ordered the bearings, pulleys, belt, and shaft from Grainger.

We used heavy slotted shelving material to make the frame. This also came from Grainger - but it was left over from other projects.

We brazed a large hex nut onto a hub that mounts on the shaft and we turn it with a large socket on the end of a speed wrench.

 It has been working for years - just needs a little tightening and adjusting from time to time. Students can fairly easily get to 120 volts - until I turn on a light.

 


One change I would make - we mounted the bearings to a couple of pieces of slotted angle and it is too flexible - hard to align the bearings so they don't bind. Plus, the bolts holding the slotted metal are also the ones that have to be loosened and tightened to adjust the belt. I would replace that with a solid block of metal and then mount that block to the frame.

 It took 2 of us about 4 hours to make.

To Stretch Your Budget, Roll Your Own!

Gary Recher is one of a group of instructors who communicate with me regularly, giving me feedback and ideas. In today's tough economy, we are all being asked to do more with less. Rather than focusing on what we don't have, I suggest we focus on what we DO have. Gary sent me this article on how he makes his own trainers. I hope it will stir your creative juices to see how you can use what is at hand to teach effectively in a challenging environment. If you have a favorite idea that you are willing to share, send it in and I will post it!

Electrical Troubleshooting Trainers

We as instructors want to provide our students with as much realistic troubleshooting scenarios as possible. We can use troubleshooting diagnostic software, manufactured trainers, and actual equipment that many times that we have to swap good parts for bad to provide troubleshooting tasks. Each has its place and can provide excellent opportunities for students’ to hone their troubleshooting skills.

Computer software can stimulate the student on various troubleshooting scenarios. This allows the students’ to develop problem solving skills without shorting out equipment or meters. However, it does not allow them to demonstrate those skills on actual systems using test equipment.

Use of manufactured trainers are many times boards that have the same components as an actual system that has trouble switches to simulate problems. The advantage of a trainer is that it allows the student to use their meter in an actual troubleshooting scenario rather than at a computer screen. Giving them the chance to use a meter and interpret their meter readings. The downside of these trainers that many times they are forced to use test points for the meter test prods rather than testing at points one would actually use in troubleshooting such as relay terminals.

Actual equipment allows students to get actual hands on experience. The limitations to using actual equipment is that to create a troubleshooting scenario the instructor or lab assistant will have to remove good components and install defective ones. This method is time consuming as the equipment will have to be set up for the troubleshooting scenario and then repaired at the conclusion of the troubleshooting session. If there is only one student this is ideal as the student can then demonstrate the removal and replacement of the defective component and then accomplish an operational test of the system. If several students have to troubleshoot the same fault there is always the downside of the fault being compromised to students that have not accomplished the troubleshooting task.

As HVAC/R technicians/instructors we are no strangers to solving problems. And there are ways to providing realistic troubleshooting scenarios without having to swap good parts for bad. Here is what our course has done that allows us to change troubleshooting scenarios using toggle switches. One of our troubleshooting stations is a cube air conditioner connected to an air handler with electric heat. On the back of the air handler a large hinged door component box was installed. Which is now becomes troubleshoot control center. Inside are mounted four motor starter rated toggle switches several lower amperage rated toggle switches and a dual run capacitor. Inside the compressor compartment the wires for the compressor and fan windings and wires spliced back to the control center. In the air conditioner’s electrical control box the contactor coil wire is unsoldered from one of the terminals. A 20 gauge stranded wire is soldered to the terminal and a second wire soldered to the coil wire. Both are run back to the control center to a toggle switch. Are you getting the idea now? With a flip of a switch there is a defective contactor. With the flip of a switch there is an open compressor or fan motor overload or run winding. The air handler cube relay was relocated to the control center. A similar relay was disassembled and the coil disabled and wires soldered to the internal terminals a hole drilled to the bottom of the relay and then through the mounting plate, grommet inserted into drilled hole, and back to control center through toggle switches. The thermostat was not immune either to our devilish modifications. By carefully grinding the current path etchings on the terminal board with a Dremel grinder wires can then be soldered to both sides of that break and then run to a toggle switch to the control center.

The downside of this is that you will have to do it yourself, and it does take time to make. The upside to doing this is that the student will be troubleshooting equipment as near world as possible and troubles can be changed with the flick of a switch from a thermostat to a fan relay to a compressor problem, etc..

This same procedure can be accomplished using manufactured demonstrators. By installing faux relays and toggle switches a demonstrator can be turned into a troubleshooting trainer.

The bottom line of this article is to hopefully to inspire you to use your mind, innovate and create the training devices that provide more realistic training situations.