There are a lot of welds on the portable frame, and I want to make it known before I start this description that each and every weld was applied with the homemade Mega Buzz Box welder.
I want to show a good example of the quality of weld the Mega Buzz Box is capable of and, for the record, no pre-heating was neccessary on the 1/16" x 1" steel tube portable frame. O K, enough bragging, let's move on!
I designed a small but sturdy frame for this portable generator. Not only will it have to support the weight of the engine and generator but, it must withstand vibrations, torque and centrifugal forces as well. This is the generator mounting plate in progress. I used a cut-wheel mounted to a grinder to fabricate the slots.
After drilling and slotting the generator mounting plate, it is checked for alignment on the frame. Once satisfied with the fit, the generator mounting plate is degreased and coated with primer.
The bolt holes for the engine and the generator mounting plate are laid out and drilled on the top rail of the portable frame. The bottom rail is tacked, squared and welded. The welds where the uprights are being erected are ground flush to permit acurate fitting. The remainder of the portable frame is fitted and tacked.
The portable frame is fully assembled and it's time to start welding. For greatest strength, each joint should be welded 100% which means every visible joint. The are places on the portable frame such as tube ends that will be difficult. I apply a good tack and let that suffice.
I flip, twist and turn the portable frame until I am sure that I have welded every joint possible. I don't want to miss a critical weld that will cause catastrophic failure during use. I take the time to be thorough. When I am satisfied that I have welded the frame, I clean and degrease the portable frame and prepare to prime.
The portable frame primed and painted.
With the Repaired B&S Engine mounted on the portable frame, it's starting to look like I'm actually building something here.
Remember this motor? It's the 3 Phase Motor Rebuild that was rebuilt specifically for this project, to begin service as a portable electric induction generator. I've mounted the generator mounting plate to the generator as well as the drive pulley to the shaft.
At this point it is hard not to get anxious trying to rush the completion of the portable however, I must stay focused to avoid making a mistake. I've come too far to fail now.
I needed an effective means of Isolating the capacitors. I chose this hardwood box to house the capacitors, outlets and wiring.
As can be seen in the photos, each phase gets a capacitor and an outlet. I took care not to mix any of the circuits by giving each phase and capacitor a number.
There is nothing that satisfies the ego like a well thought out plan comming together. All of the planning, physical effort, victories and disappointments blend together to become accomplishment.
The information I could gather for the Bronzoni 3 Phase Motor and the B&S 158cc Engine is obscure. From what I could determine, the Bronzoni is a European built 3 Phase Motor that is rated 4.8 KW at 6 HP and, the B&S 158cc Engine is approximately 5 HP with a rotational speed of approximately 3300 rpm.
When I pulled the cord and fired up the B&S engine, I took a voltage reading from each phase and measured 250 vac-rms per output. I was amazed that the portable began generating from the first start and concerned that the per phase voltage was so high.
My design protocol was to provide a range of RPMs' to give a small degree of regulation as the load placed on the portable generator increases. I started with a pully ratio of 1.426 to 1, (3.35"D engine, 2.25"D generator), which resulted in 250 volts per phase. To bring the voltage within an acceptable range, I reduced the pully ratio to 1.063 to 1, (3.35"D engine, 3.15"D generator).
At this ratio and with no load, the highest generator speed is 3507.9 rpm producing 210 vrms at 50 Hz which eliminates any frequency dependent American devices from being powered with this portable electric generator. The lowest speed produces 110 vrms at 41 Hz. Light bulbs are not frequency dependent and, from what other builders report, circuits behind transformers work as well making this portable induction generator a source for emergency back up power.