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Thread: Generator build

  1. #1
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    Default Generator build

    I have been slowly building a decent generator for running the house and also for site work. I had a Kubota D950 engine here to mate to an alternator. The engine is 17hp continuous at 3000rpm.

    I ended up purchasing a Mecc Alte 11kva AVR bare shaft generator head and learning a bit about power factor in the process. The generator is coupled to the engine via a jaw coupling.

    Various purchased from China, like the fuel tank, emergency stop solenoid, and local purchases like the electrical outlets I cobbled together something that looks a bit rough compared to commercial units but seems to work well. A local electrical repair centre wired up the outlets and circuit breakers and test ran it with a 40 amp load and they said it handled it well. It has been wired up as an isolated supply as it will be used for house backup power you can not have a MEN wired generator hooked up to a MEN wired installation as the RCD on the generator will just cut out. Our local mains electricity supply outages seem to be increasing in the length of time it takes for repairs.

    It has 2X15 amp outlets and a 32 amp outlet. It is a pity in Australia the 15 amp outlet gained such widespread use leading it to become a common outlet as I feel it is too close to the 10 amp and we would have been better served with 20 or 30 amp outlets being more common with appliances easily available to suit. I would like a decent stick welder (250 amp) to run off the 32 amp outlet but I doubt they exist in Australia.

    The engine has been fitted with a electronic engine watchdog and will stop the engine with either low oil pressure or high engine temperature (via a sensor that sits under a bolt on the engine head). Attached to a solenoid that pulls in the decompression lever to stop the motor in case of something going wrong.

    It weighs about 320kg and I can cart it around with my dingo.


    20190619_140058.jpg 20190619_140212.jpg
    Gold, the colour of choice for the discerning person.

  2. #2
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    Nice build.

    WRT a 250A stick welder, my single phase 250A Unimig is rated at 35% duty cycle @250A (MMA mode). 29A input
    Specs for the current model: https://unimig.com.au/product/unimig...g-mma-compact/

    Not sure if a Unimig meets your "decent" classification though

    Steve

  3. #3
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    Yes very useful.

    Got a similar sized one -- store bought.

    So all prepped now for Govt energy policy!!!!
    www.lockwoodcanvas.com.au

    I will never be the person who has everything, not when someone keeps inventing so much cool new stuff to buy.

    From an early age my father taught me to wear welding gloves . "Its not to protect your hands son, its to put out the fire when u set yourself alight".

  4. #4
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    Nice set up. Just a suggestion, if the alternator/generator has a circuit board, get one as a spare.
    We've got one at work that's about 15 years old, only done 400 hours, and the "electrician" blew the circuit board.
    Worst part is there are NO SPARES, anywhere!!!!!!!!!!!
    We now have a 36kva unit with low hour Ford Industrial Motor that won't generate power.
    Kryn
    To grow old is mandatory, growing up is optional.

  5. #5
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    You did a great job there! Looks a lot more reassuring than my 12hp commercial 22A (supposedly) standby generator.... Looking forward to longer-term evaluations in the future, especially of the generator part.
    Cheers, Joe
    again completely retired - more time to contemplate projects and spend more shed time....

  6. #6
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    Quote Originally Posted by KBs PensNmore View Post
    Nice set up. Just a suggestion, if the alternator/generator has a circuit board, get one as a spare.
    We've got one at work that's about 15 years old, only done 400 hours, and the "electrician" blew the circuit board.
    Worst part is there are NO SPARES, anywhere!!!!!!!!!!!
    We now have a 36kva unit with low hour Ford Industrial Motor that won't generate power.
    Kryn

    There are a few universal control boards out there that will fit many different brands of generators.
    Genaust AVR Automatic Voltage Regulator Generator genaust avr

    This generator does have an electronic control board and I chose this head specifically because of the improved voltage regulation they provide. In my experience the capacitor regulated smaller generators put out not very clean electricity and the volts drop the higher the load.


    One thing I was slightly disappointed with my build was the cost to wire the mains electricals up. I thought $500 a bit excessive when I had everything installed and supplied and all that had to be done was run wires.
    Gold, the colour of choice for the discerning person.

  7. #7
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    Quote Originally Posted by .RC. View Post

    One thing I was slightly disappointed with my build was the cost to wire the mains electricals up. I thought $500 a bit excessive when I had everything installed and supplied and all that had to be done was run wires.
    $450 of it was probably to cover the insurance needed.....

    I've got an old 250A @ 60% duty cycle stick welder that can run off of single phase. Never use it any more. Not sure about freight to you though. I won't be back home until early August so you've time to think about it - email me if interested. It's one of the old copper core units.

    PDW

  8. #8
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    You could have had my 100kvA unit for free if you paid the freight to QLD. You would also pay the fuel bill for the 6 litre turbo Cummins in it.The control board had three rows of instruments . The technician had noted in the log book " bloody miracle the unit actually ran without any glitches for once" The fuel tank was built into the floor. A massive radiator . 3 phase gene of huge proportions .

  9. #9
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    Quote Originally Posted by PDW View Post
    $450 of it was probably to cover the insurance needed.....

    I've got an old 250A @ 60% duty cycle stick welder that can run off of single phase. Never use it any more. Not sure about freight to you though. I won't be back home until early August so you've time to think about it - email me if interested. It's one of the old copper core units.

    PDW
    I imagine freight would be $$$$$$$$$$$$$$$$. I have access to a 225 amp lincwelder, but they have a paltry 25% duty cycle. Usually if I have to start burning 4mm welding rods it means a big job.
    Gold, the colour of choice for the discerning person.

  10. #10
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    Very nice build. Yeah $500 does seem very excessive. We paid $300 for our at Mallacoota. It's only a matter of running the wires to a power socket (for generator) thats hooked to your house mains board, an auxillary switch and a change over switch fitted to the main board.
    All The Best steran50 Stewart

    The shortest way to do many things is to do only one thing at once.

  11. #11
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    Well the changeover switch in our main meter box has been fitted.

    Amusingly on generator power the power meter runs backwards. I doubt it is supposed to do that and should be isolated when on generator power. And one house is not getting electricity.

    But the generator runs the phase converter really well and runs all the motors. The motor startup might even be a bit snappier then mains power.
    Gold, the colour of choice for the discerning person.

  12. #12
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    Quote Originally Posted by .RC. View Post
    Well the changeover switch in our main meter box has been fitted.

    Amusingly on generator power the power meter runs backwards. I doubt it is supposed to do that and should be isolated when on generator power. And one house is not getting electricity.

    But the generator runs the phase converter really well and runs all the motors. The motor startup might even be a bit snappier then mains power.
    The Electrician has done something wrong, it nearly sounds like he's set the Generator switch up like you would a Solar System. I'm not certain that the meter is supposed to run backwards though either (I'm not an Electrician just an Outboard Mechanic). I would assume like myself you are only using the Generator as a back upin the event of a power failure which as you had said do occur fairly often (not your exact words). The mains power is supposed to be isolated when the Auxillary (Generator) source of power is being used. I would say that he has isolated the wrong side of the Mains meter. I think I'm correct in what I'm saying in that what he's done by making the Mains meter run backward would be illegal. I hope you get it sorted.
    All The Best steran50 Stewart

    The shortest way to do many things is to do only one thing at once.

  13. #13
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    It is an old meter and the internet says these old ones are happy to run backwards hence why on solar installations they replace the meters with digital ones.

    It is a win win.

    Not paying for electricity when on generator and reversing the mains electricity I had already used.

    So rather then paying 28c/kwh, I am getting 56c/kwh.

    But unfortunately the boss electrician is coming back to have a look.
    Gold, the colour of choice for the discerning person.

  14. #14
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    Hi Guys,

    If the generator is not isolated from the incoming mains supply it creates a dangerous condition for anyone that may have to work on a line that they think is dead.

    Solar grid tie inverters have incoming supply sensing that shuts them off and prevents them feeding power into an isolated line. Basically if the supply frequency disappears they simply shut down and cease to supply power.
    Best Regards:
    BaronJ.

  15. #15
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    I am not sure how it was wired but the boss electrician came back surprisingly quickly and fixed the problem.

    Now the generator can not run the phase converter properly. Just not enough oomph. It will get it started on the third attempt, but the limit is running 3hp motors. Everything bigger it just cuts out from low voltage.

    Came across some UK welder manufacturers. They make large capacity single phase machines. Mig, Tig, arc and plasma cutter, the oxford plasma cutters even have a "heat" function.

    https://www.oxfordwelders.co.uk/index.html

    https://www.technicalarc.co.uk/index...l-compact-migs
    Gold, the colour of choice for the discerning person.

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