Priority Of The Alternator Raised Again

I haven’t been working on the new alternator because it arrived just as planting season was getting going but last night a terrible wall of storms passed by and knocked out the electrical utility again. Last year it was 5h. This time it was 16h. Ouch. We did bail the sump a couple of times but the ground had dried and the rain was brisk but short. There wasn’t a lot of water to dump. We were able to dump water into the septic tank without it backing up. When the power came back, the septic tank alarm went off but now that’s pumped out too. The greatest excitement resulted from a loose chair getting involved with my grapes and two bedroom windows were not closed… Some bundles of garden-edging rolled over. Those things are heavy. Winds must have been brisk.

Near the end, I chatted with a neighbour who had a 9KW alternator running on his driveway. He offered power if we were in need. He happened to know that the failure was a whole substation that needed replacement. It was the same point of failure as last year. A mobile unit had been installed and it failed this year…

On the bright side, when my Internet access was restored I learned that TLW’s new
Odroid-C2 thin client was on a truck heading our way so today is the day we could free another seat from x86, replacing an ancient VIA thin client. At the same time, I learned my new gigabit/s switch was on its way. So, things are looking up and the storm which spawned tornadoes, and baseball-sized hail (further west of us) did little harm here. It did provide a fantastic horizon to horizon double rainbow as it departed. We have pictures… but I didn’t take them and I didn’t think of using hugin at the time.

Before I could finish this the Odroid-C2 arrived. It’s beautiful but they sent the wrong power-plug. Fortunately, having worked in Saudi Arabia, we have adapters, so it’s all good. I did have one other problem. The case was difficult to pry apart. A video gave a clue that one has to push in on some inner tabs and I also found I had to insert a pencil to push out on the other part of the tab. After that it went together well except that I did not have a fine enough screwdriver. Tape will have to do…

About Robert Pogson

I am a retired teacher in Canada. I taught in the subject areas where I have worked for almost forty years: maths, physics, chemistry and computers. I love hunting, fishing, picking berries and mushrooms, too.
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6 Responses to Priority Of The Alternator Raised Again

  1. dougman wrote, “what was the KVA and voltage rating on the alternator?”

    It’s 30KVA and 400V 3-phase. I will draw single phase for the welder and small motors and lighting. If I were to drive larger loads I would do it through an inverter. An inverter really pays when the loads are variable as a household is. One can reduce the RPM/voltage for lighter loads and ramp them up for heavier loads, saving some wear on the engine and fuel. In the short term the most important feature is reliability and the diesel on the tractor is very simple and reliable. It can run 24×7 for months with nothing but oil-changes whereas the usual high-rpm direct-coupled gasoline-powered alternators are toast in a few hundred hours, 1000 max. My diesel is guaranteed for 1500h. Clearly, a gasoline generator would do for most of my situation but I fear the longish outage that mother nature can provide. We are very dependent on electricity for the standard of living to which we’ve become accustomed. A diesel generator is very reliable and affordable. It’s very expensive to run but that’s secondary to being without electricity.

    Recently my province has decided to promote self-sufficiency so there may be subsidies and options to sell power from photovoltaic arrays. I could dig that but it’s way more capital-intensive.

  2. dougman wrote, “You need a 40HP engine or better to drive it.”

    I have an M.Sc. in nuclear physics. I understand things like this. I don’t need to get 30KW out of this alternator now, just enough to drive my current loads. A small gasoline engine would do a few things. My 18HP diesel would do much more, like run the welder quite well. I normally work at 100A X 25V, 2.5KW, 7KVA. If I wanted to run most of the house, indeed a 40HP engine would be better. It still would not run my heating system properly but I could add baseboard heaters to work with that. The Chinese do sell nice 40HP diesel engines for their gensets, but it would be a waste for my current light loads. Another difference with 40HP, is that I would likely have to direct couple instead of using belts. Belts are better for what I intend to do in the near future. They are just more flexible. Because the cost of shipping was so large, I just ordered the biggest alternator I will ever likely need and will hook it up to the most convenient size/type of prime mover. It will actually help starting the diesel as it will be a bigger flywheel.

  3. dougman says:

    Actually never mind the voltage, I found the value for your alternator. Using 0.745699872 × HP = kW as my basis, and supplying a 5HP prime mover. You will only NET ~3.7kVA. If you add inductance to the circuit, then your circuit values change to ~2.96kW. Assuming the alternator is designed for a 0.8 power-factor, which most are.

    So in essence, you are woefully undersized. You need a 40HP engine or better to drive it.

  4. dougman says:

    Ok, what was the KVA and voltage rating on the alternator?

  5. dougman wrote, “I still like to know how you plan on driving this alternator.”

    I think I will use the rototiller as soon as the soil dries a bit and then move its engine to a frame with the alternator mounted on it. I have pulleys and v-belts ready to go. The engine will run about 2200rpm and the alternator at 1800 rpm. I was thinking of using a smaller gasoline engine but that would be as much work but without easy expansion of load. This setup will be good for my welder as well as the pumps, emergency lighting, etc. I could arrange to mount the alternator on the front of the tractor but there would not be much room for distribution panel and the welder unless it’s on a trailer that I would bolt onto the tractor. That seems cumbersome. I want something more mobile.

  6. dougman says:

    Had you bought a REAL tractor coupled with a $2K 10KW pto generator, you would still have power.

    I still like to know how you plan on driving this alternator.

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