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Thread: Single phase to 3 phase

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    Question Single phase to 3 phase

    Ive been trying to figure out if there is any other way to convert single phase to 3 phase. I know it can be done with the motor and all, but is there another way? I need 45amps. tops. You would think being an electrician I could figure it out I heard you can use rectifiers or somthing like that.
    Any ideas?
    Thanks!
    DJ Matt
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    Rectifiers? no, you can create a really bad kind of phase converter with a bunch of capacitors, but this will not fare well for running a laser. The best way would be to use a single phase to 3 phase inverter frequency drive but they are $$$$

    The cheapest and easiest way is to use a large motor and some run capacitors to make a rotary phase converter. 45 amps of 3 phase is nothing to mess around with - you'd need some serious cabling to the phase converter to prevent voltage sag.

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    Quote Originally Posted by djmatt View Post
    I heard you can use rectifiers or somthing like that.
    Any ideas?
    Thanks!
    DJ Matt
    I think what you heard probably had more to do with rewiring the rectifiers in a gas laser PSU so that you can use it with either a single OR three phase supply depending on how you connect it.
    I have a couple of lexels modified to do that. Getting rid of the buck/boost also makes the PSU slightly more manageable during transport. You do have to be a bit careful with details like filament current and starter supply however.

    European version of Lexel 95 are already a bit of a pig to start with since they use half wave rectification which plays havoc with the sound guys systems due to the wobbly neutral line if sharing a generator.

    Also you can get three phase to single phase transformers but they COST !!!

    cheers

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    You're probably going to need to beef up the filtering capacitors for running on single phase, and as mentioned need to keep a closer eye on the filament voltage.

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    Quote Originally Posted by MarioMaster View Post
    You're probably going to need to beef up the filtering capacitors for running on single phase, and as mentioned need to keep a closer eye on the filament voltage.
    Your dead right, forgot about them blue beasties!
    Did the mod many years ago.

    Cheers

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    Quote Originally Posted by catalanjo View Post
    Your dead right, forgot about them blue beasties!
    Did the mod many years ago.

    Cheers
    Um, Perhaps I'm missing something here, but without the buck/boost, how did you keep the passbank voltage less then 60V in Europe?

    Steve
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    Quote Originally Posted by djmatt View Post
    Ive been trying to figure out if there is any other way to convert single phase to 3 phase. I know it can be done with the motor and all, but is there another way? I need 45amps. tops. You would think being an electrician I could figure it out I heard you can use rectifiers or somthing like that.
    Any ideas?
    Thanks!
    DJ Matt

    Matt, since you have SPs, there is no easy, cheap conversion using a solid state variable speed motor drive unless you use a buffer transformer. The buffer is quite small, on the order of 25-30 pounds. So your option is a rotary converter, either a Ronk or home made one with a motor, or a VSD with a buffer transformer.

    Running the SP 265 on single phase requires beefing up the main inductor and adding a huge amount of filter caps. None of which would fit in the case.

    The filter components for a ion laser power supply are size dependent on the ripple frequency, being much smaller for higher frequencies. Single phase ripple is 120 hz,and the filter parts are huge. Three phase ripple is 360 hz, so the parts in the existing power supply are much, much smaller then they would be at 120 Hz.

    The SP265 inductor is KNOWN to melt at 120 hz after a short time.

    Steve
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    Quote Originally Posted by mixedgas View Post
    Matt, since you have SPs,
    The SP265 inductor is KNOWN to melt at 120 hz after a short time.
    Steve
    Sorry I didn't know we were talking about SPs.

    Cheers

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    Quote Originally Posted by mixedgas View Post
    Um, Perhaps I'm missing something here, but without the buck/boost, how did you keep the passbank voltage less then 60V in Europe?
    Steve
    Shit every time I try to avoid being long winded something gets left out!

    More than thinking outside the box ,it's a question of mounting the buck/boost outside the box. Most of us in EU have 380/220 external trafos anyway, since 220 three phase is very rare. (that's why the EU lexels are half wave rectified).
    So you still lug the weight around just that its in three lumps instead of two lumps.
    PSU,Buck/boost,380/220, (or in the case of the HWR lexels two lumps instead of one.)

    We also have somewhat unreliable water supplies (at least in Spain), which is another can of worms altogether. I use 50l pressure tanks (with anti-return valves) sitting on bathroom balances, with micro-switches in the interlock lines. Too little (or too much) weight in the tank and laser switches off with still enough water to cool the tube, being pushed through by trapped air pressure. Also very useful in closed circuit kooling systems.
    All in all lots of junk to lug around.

    Still, solid state cheap blue just kicked all that out of the window. Any one want to buy some old gas lasers?

    Cheers

    PS. Sorry to get off topic!

  10. #10
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    \
    We also have somewhat unreliable water supplies (at least in Spain), which is another can of worms altogether. I use 50l pressure tanks (with anti-return valves) sitting on bathroom balances, with micro-switches in the interlock lines. Too little (or too much) weight in the tank and laser switches off with still enough water to cool the tube, being pushed through by trapped air pressure. Also very useful in closed circuit kooling systems.
    All in all lots of junk to lug around.

    Well, the bathroom balences are a new wrinkle, and a useful one at that, but we have similar rigs in the states, plus we use(d) booster pumps to suck extra water out of the line. Ice machines in clubs consume massive amounts of water, so I would rather deprive the ice machines and automatic dish washers of flow then loose the show

    Steve
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