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Thread: Mixing with single phase

  1. #1
    New Member Frikkiemieny's Avatar
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    Question Mixing with single phase

    Please help,
    I mixed a waterproofing compound from a factory with a 3 phase motor, but lost the factory due to economics.
    I would no I must try and mix from home but only have single phase.
    The question
    Can I use a single phase motor.
    Can I run direct running (from motor)
    Should I run with pulleys

    The thickness of the product I am using work as follows
    Start with water so the motor will mix easily then I add chemicals to make it thicker, the final thickness would be something like paint

    Regards

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    Diamond Member AndyD's Avatar
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    It sounds like you're building the mixer yourself from scratch or are you trying to convert your existing 3-phase mixer into single phase?

    If you're making a mixer from scratch you really need to work backwards to end up with a specification for the motor. The motor size would depend on the shaft power required to drive the mixing paddle at the required rotational speed in your specific paint product. It will be determined by the product viscosity, the rotational speed and the design of the paddle which will dictate the mechanical power required and therefore the size of motor and the size and type of electrical supply.

    Designing this kind of system isn't something I'd recommend you try unless you've got experience in this area. You may find off-the-shelf mixing paddles are available where the manufacturer gives you specifications about the power requirements in a range of products at a range of speeds, if so I'd suggest you go that route or maybe copy an existing design from a mixer that suits your needs if you're intending to fabricate your own components.

    In answer to your questions, you may be able to use a single phase motor depending on the size of your mixer. You could configure the drive as either direct or as a pulley system or via a gear box depending on the RPM of motor, the RPM required for the paddle and also depending on whether you need variable speed or not. It also depends on whether there's a single mixing paddle or whether there's a slow rotating bowl scraper with a faster rotating mixing blade in the centre.

    If you're trying to convert an existing mixer from 3-phase to single phase please attach a picture/photo of the data plate that's on the motor or give details such as make and model number of the mixer.
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    New Member Frikkiemieny's Avatar
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    Hi Andy,
    Thank you for the advice.
    I have a mixing frame I used with the 3 phase motor Photo of plate, and if possible to convert this motor to 1 phase I will be so happy.
    Otherwise I will have to get a 1 phase motor, if this motor is converted and I lose some RPM and talk it will not be a problem as the motor is to strong.
    This viscosity as I said is that of paint, and is thixotropic , the blade I am using is a high speed shearer and were using it as direct drive.
    The specs
    4 Kw A 8.6 and RPM 1425
    See photos thanks for your help it is appreciated.
    Frikki

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    Diamond Member AndyD's Avatar
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    There are ways to run a 3-phase motor on a single phase supply but 4kw is too large, the capacitors you'd need would be enormous, you would lose torque and also there's a fair/good chance the motor would overheat depending on how long it needs to run. Replacing the motor with a single phase equivalent won't be easy, most ranges of single phase motors only go up to 2.2 or 3kw. It is possible to get a 4kw 4-pole single phase motor but it would be expensive and the start current would be pretty high...maybe too high for a domestic electrical supply.

    I don't see an easy or cheap option here, I'd suggest maybe investigate selling your 3-phase mixer and purchasing a smaller 2.2kw single phase one and do smaller batches. I honestly think this might be your cheapest and least risky bet in the long run.
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    Diamond Member Justloadit's Avatar
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    Maybe a cheaper way, is to get a 3 phase 7.5KW generator, and run it when you do your batch.
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    Hi

    To run a motor on a generator, direct on line, you would need to size the genset at around 6 times the motor size - 4Kw motor will need a 24KW genset unless you fit a soft start to reduce in rush current.
    It will be an expensive exercise - Genset will set you back around 50K

    If you are prepared to through money at the problem and since you state that the motor is over sized for the job try a soft start or VSD single phase in 3 phase out and purchase a motor to the max soft start available.
    I would also speak to the suppliers of soft starts and see if you could set up say a 2,2Kw single in 3 out soft start to run the present 4 kw motor - You would be electronically reducing the motor to a 2,2kw motor -

    You will still be looking at around 15K for both but cheaper than a 3 phase generator and all the hassles that will go with maintaining the genset.

    Andy's plan of changing to a designed single phase mixer may still be the best solution

    The other option is to change your domestic supply to a 3 phase supply - I would estimate the municipality cost to upgrade the supply at around 126K and then an electrical contractor to carry out the necessary at 30K - Again throws you back to buying a ready made single phase mixer

    There is unfortunately no cheap quick fix solution.

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