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Three phase to single

Discussion in 'Electrics UK' started by Tigercubrider, 22 Apr 2020.

  1. Tigercubrider

    Tigercubrider

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    hi
    At work we have an old startrite bandsaw. It's in storage and we are locked out.
    I was chatting to one of the guys and he thinks it was three phase?
    No idea of power used or model- it's the green floor standing ones that are everywhere

    We could use it in a metal work area but are moving out soonish so don't want to spend money on installing a three phase system .
    We do have a 16A feed on ceeform- otherwise just 13a sockets

    I'm aware of guys buying industrial stuff and running it in home workshops, converting to single phase.

    My question is a guess as to the cost of a suitable conversion box and any pitfalls.
    Thanks
     
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  3. JobAndKnock

    JobAndKnock

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    Google Transwave for converters.
     
  4. ericmark

    ericmark

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    It depends on how many motors, and how the motor is wound, we had a lot of small motors 400 volt star and 230 volt delta and the inverter to run a 230 volt delta motor from 230 volt single phase was quite cheap, it also got rid of inrush problems and gave some speed control, but the larger motors were 690 volt star and 400 volt delta and by starting in star mode with just 400 volt it started motor moving then it would be turned to delta once turning, the cost of inverters or drives for these motors was far more expensive as had to step up the voltage.

    Where the problem lay was with multi-motors, so coolant motor, as well as main motor, to use an inverter to get 400 volt three phase from 230 volt single phase with standard direct on line starting is a huge load on the inverter when starting, and even if the inverter will take it the load can cause a massive volt drop, what is required is rotating mass, this will absorb the start load, be it a rotary inverter, or a sequence of starting motors so those turning assist next one to start does not matter, but in essence it gets complex.

    Using an inverter direct to drive a motor means the inverter also controls start load, so there is not the same problem with inrush and volt drop, but using an inverter as stand alone is another story. My fridge and fridge/freezer are both three phase with inverter controls as they actually work better than having a single phase motor, less likely to stall, can work better with volt drop, smoother, etc. But clearly you can't read motor plate at the moment, cross fingers and hope it is 230 volt delta. But may need to renew any coolant motor or control system.
     
  5. flameport

    flameport

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    Without that info it's a dead end.

    However for a single piece of used equipment, a phase converter is likely to cost more than the equipment itself is worth.
    Probably cheaper to remove the motor from it and fit a single phase motor instead.
    Or possibly fit an imported no-brand VFD to run the 3 phase motor.
     
  6. Tigercubrider

    Tigercubrider

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    Cheers guys
    Just trying to figure things while stuck at home
     
  7. JobAndKnock

    JobAndKnock

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    Assuming that it is a "boxy" model, and is a woodworking safe (Startrite made a lot of metal saws and thre succesor company Klausimg, still do), the two most common model types are the 351 or 352, which were 14in wheel machines with a 0.75kw motor - they actually look like they are sitting on a box and are below head height for a six footer - whilst the other common model was the 501 or 502, a larger machine altogether (just over 6 feet tall) with 20in wheels and either a 1.5 or a 2.2.kW motor. There were also metal saws, but they tend to look a bit more rounded at the top corners
     
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