Re-wiring European Generator?

Discussion in 'General Electronics Chat' started by handyalbert11, Feb 4, 2011.

  1. handyalbert11

    Thread Starter New Member

    Feb 4, 2011
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    I recently acquired a Kubota Generator for a good price, only problem is its an Australian model that only supplies 240v. My first thought was that if you have 240 you must have 120. But apparently that is not true in this case, only 240. Is there any way to re-wire the generator to make 120? Or am I stuck trying to find another generator end? Thank you
     
  2. gerty

    AAC Fanatic!

    Aug 30, 2007
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    Probably the easiest/cheapest thing to do is to add a transformer of the appropriate size. That would allow you to keep the 240v and have the 120v,
    and you wouldn't have to cut into anything.
    On a side note, is it 50hz by any chance? I don't know if that's what they use in Australia or not, but if you need 60hz you might want to check that.
     
  3. handyalbert11

    Thread Starter New Member

    Feb 4, 2011
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    It is a 50hz model but that was the first thing we changed by adjusting the driving speed of the diesel engine. The transformer was something I was also looking into but i was hoping there was some other way.
     
  4. debe

    Well-Known Member

    Sep 21, 2010
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    Be handy if you could get a circuit for it as some generators have a 110V tap in the windings. My old Honda does.
     
  5. thakid87

    Active Member

    May 23, 2009
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    Is this a 2 or 3 wire system? Have you tested it to see if it runs after changing the speed on the fuel pump? Almost always the changes need to be done on the engine and also on the control panel.

    Who assembled the generator?
     
  6. someonesdad

    Senior Member

    Jul 7, 2009
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    I agree with gerty. You should be able to find a suitable autotransformer. A few decades ago I bought one for my 120 VAC 1 hp metal lathe so I can run it on a 240 VAC circuit. You might also find that you want to keep the 240 VAC output, as it might be useful for some appliances that can be run at those voltages. For example, a friend sent me a beautiful lab hot plate that runs on 240 VAC. I wired my shop to have 240 VAC and 120 VAC at all the outlets, so this means I can use the hot plate with no sweat.
     
  7. handyalbert11

    Thread Starter New Member

    Feb 4, 2011
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    http://generator.kubota.jp/j/j_108_aus.html

    The model number on the generator end itself is J108A1. I dont know if someone else can get any more info than this? I will keep looking also.

    This was the best info i could find on the generator, it does run at 60hz now just 240 only. I do want to keep the 240 output but also need 120. Space is somewhat limited so i would like to stay away from the transformer but if thats the only way might have to make it work. Thank you for all the help!
     
  8. tracecom

    AAC Fanatic!

    Apr 16, 2010
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    Genheads are wound on specialized winding machines with custom tooling for each model to be wound. Rewinding one by hand would be all but impossible even if you had the design parameters. Having been in the generator manufacturing business for eight years, I can tell you that if the genhead you have doesn't already have two 120vac windings, your only realistic option is to replace the genhead with one that does. (120vac power can be drawn from each of the windings, or the two windings can be connected in series to provide 240vac.)

    Genheads are fitted onto tapered driveshafts that extend from the engine crank; removing one without the proper equipment can be done. Sometimes they come off easily and sometimes they are extremely difficult to remove. If you find a replacement genhead, you should be sure to get the wiring harness and control panel that goes with it because they are difficult to fabricate by hand. Your best source for a genhead and control panel might be a company in Georgia called Pramac.

    I would strongly advise you to remove the genhead from the engine in your generator before you try to obtain a new genhead. That way, you can be sure of the engine shaft taper and bolt pattern when you are looking for a replacement genhead. You also need to be able to specify any special features which you want wound into the genhead; idle control and 12vdc charging both require special windings.

    Doing what you want is possible, but it isn't easy. Good luck.
     
  9. handyalbert11

    Thread Starter New Member

    Feb 4, 2011
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    Thank you very much for the reply, very helpful info. Looks like i will be going with the transformer. I am planning to power a standard size home refrigerator, 22" flat screen TV with a home theater system or an XBox, 2 or 3 lights, a microwave, and other small accessories. Any reccomendations on a good transformer to buy and where from? I would like to be able to wire it into a breaker panel not have to plug each seperate item into it.
     
  10. tracecom

    AAC Fanatic!

    Apr 16, 2010
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    I don't know of a source for a transformer, however if you are planning to connect to your house wiring, you should use a "transfer switch" to provide failsafe isolation between the genset and the mains. Depending upon your local electrical codes, this may require a licensed electrician.

    BTW, the genset you bought looks good; the diesel engine should be better than gasoline: longer life and easier fuel storage. In order to get the frequency up to 60 Hz, I presume you had to increase the run speed of the engine from 3000 rpm to 3600 rpm? I'm no expert on diesel engines, but that seems quite fast. (Diesel generator engines often run at 1800 rpm to reduce noise.)

    And if the genhead design was optimized for 50 Hz, you may find it to lose some efficiency at 60 Hz. Before you spend a lot more time and money, you might want to load the generator down to check its power output, and look at the output on a scope to see how much THD (total harmonic distortion) is being produced.

    I'm sorry to mention so many complications, but it might be better to think them through now rather than in mid project.

    Good luck.
     
  11. ian_gregg

    New Member

    Jan 19, 2011
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    Back to basics. If you look at the wiring from the stator of the generator and there are 4 wires from the stator linked in series and connected to the AC output then you have two 120V windings. If there are only 2 wires from the stator connected directly to the output then you only have one 240V winding. But you said you wanted both 120 and 240V, if you want them both at the same time you definitely need a transformer.
     
  12. tracecom

    AAC Fanatic!

    Apr 16, 2010
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    Actually, it's possible to draw 120vac from one winding while drawing 240vac from both windings in series. Now, if you want all the 120vac the genhead is capable of, then you need both windings in parallel.
     
  13. thakid87

    Active Member

    May 23, 2009
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    I second the use of a transfer switch. Where are you located?
     
    Last edited: Feb 8, 2011
  14. handyalbert11

    Thread Starter New Member

    Feb 4, 2011
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    Thank you for all the replies/info. I should explain that this is going into a custom built motorhome. (Basically very large box placed on the frame of a Kenworth T2000) so this is the main power. I will have to check and see how many lines are coming off the stator.
     
  15. marshallf3

    Well-Known Member

    Jul 26, 2010
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    A transformer capability of that conversion will not be inexpensive, write to the manufacturer as it may already be 120 VAC capable.
    As mentioned above many are capable of 120 VAC x 2.
     
  16. handyalbert11

    Thread Starter New Member

    Feb 4, 2011
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    2 wires from the stator, so any recommendations on a transformer for my situation?
     
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