single phase to 3 phase converters

lazza
lazza Solar Expert Posts: 336 ✭✭✭
in Advanced Solar Electric Technical Forum #1
HI Forum

We've been looking at powering some farm buildings. The problem is that although most of the equipment is single phase, there is a small 3-phase pump for irrigation (around 300W), that needs to be powered.

Are there reliable single phase to 3-phase inverters that can resolve this issue??

thanks
Larry
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Comments

  • ramloui
    ramloui Solar Expert Posts: 109 ✭✭
    #2
    Re: single phase to 3 phase converters

    You may consider one of these single to three-pahse voltage transformers: [h=3]http://www.mcmaster.com/#rotary-phase-converters/=uhpxww[/h]Cheers!
    Off-grid cabin in northern Quebec: 6 x 250 W Conergy panels, FM80, 4 x 6V CR430 in series (24V nominal), Magnum MS4024-PAE
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #3
    Re: single phase to 3 phase converters
    lazza wrote: »
    HI Forum

    We've been looking at powering some farm buildings. The problem is that although most of the equipment is single phase, there is a small 3-phase pump for irrigation (around 300W), that needs to be powered.

    Are there reliable single phase to 3-phase inverters that can resolve this issue??

    thanks
    Larry
    You have basically two choices:

    1. A rotary phase converter (not a simple transformer, since it relies on moving parts.) More like a motor generator in which the motor and the generator share windings. Kind of like the way an autotransformer works. :-)
    2. A solid state converter. For a small motor, the least expensive way to get this, and one which gives you the added advantage of soft start, would be to get a Variable Frequency Drive (VFD). By following the manufacturer's ratings and instructions you can drive a VFD from a single phase source.
    SMA SB 3000, old BP panels.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,626 admin
    #4
    Re: single phase to 3 phase converters

    ramloui posted information about "rotary phase converters"...

    More or less, take a three phase motor and connect it to a single phase power supply. Start the motor turning (pull on a rope wrapped around the output shaft, or use a capacitor start module).

    Once the 3 phase "rotary converter" is up to speed, you can now take the three wires from the converter and connect them to other 3 phase motors. The rotary converter acts a bit like a "motor generator" and supplies the missing "phases".

    These work surprisingly well. Helped a friend build an entire machine shop filled with 1-5 HP (1-4 kWatt) 3 phase motors off of single phase 240 VAC power. Ran everything off a 3 phase 5 HP motor (even used a small motor and belt to get the three phase motor up to speed originally).

    If the three phase 300 Watt motor is not heavily loaded, you can get single to 3 phase starter/controllers (capacitor+voltage sensing relay). Starts the three phase motor and then the motor runs on single phase AC--Will also work pretty well (make sure the motor does not pull too much current on its single phase and overheat, may also have lower starting torque--So for positive displacement pumps, may have trouble starting).

    http://www.phase-a-matic.com/StaticDescription.htm

    There is a lot of information on the web and you can build them yourself.

    The rotary phase converter does waste a lot of energy--May not be the best choice for off grid power system (unless it is relatively small vs overall system size, hours of use per day).

    The "Static Converter" works very well, but you need to "derate" the motor to lower output power (to prevent drawing too much current and overheating/difficulties starting).

    Lastly, there is the VFD (variable frequency drive). Get a single phase in, 3 phase out. Would probably be a very good solution to your problem.

    Of course, it appears that VFDs are MSW output (modified square wave) for the most part, which can be hard on induction motors (single or three phase), so monitor the motor's running temperature on the VFD to make sure it does not overheat. And/or replace with motor rated to run on a VFD.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • CDN_VT
    CDN_VT Solar Expert Posts: 492 ✭✭✭
    #5
    Re: single phase to 3 phase converters
    lazza wrote: »
    HI Forum
    there is a small 3-phase pump for irrigation (around 300W), that needs to be powered.

    Are there reliable single phase to 3-phase inverters that can resolve this issue??

    thanks
    Larry

    For only one 3 phase 300w pump , I'd change the motor drive to single phase , for the 3 phase converter idea , huge waste in converting ..


    VT
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  • lazza
    lazza Solar Expert Posts: 336 ✭✭✭
    #6
    Re: single phase to 3 phase converters

    Hi, thanks for all your replies

    I'm leaning towards either a solid state converter or changing the motor of the pump-

    Does changing the pump motor mean rewiring, or buying a new motor?
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  • Aguarancher
    Aguarancher Solar Expert Posts: 315 ✭✭✭
    #7
    Re: single phase to 3 phase converters

    You will need a new motor. Do you have a picture of the pump or of the face plate on the pump motor showing the specs?
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  • lazza
    lazza Solar Expert Posts: 336 ✭✭✭
    #8
    Re: single phase to 3 phase converters

    Not yet, but may be able to get a pic this week
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  • peakbagger
    peakbagger Solar Expert Posts: 341 ✭✭✭
    #9
    Re: single phase to 3 phase converters

    Small VF drives that can take single phase in and put three phase out are cheap. They also can usually be programmed for a soft ramp start which reduces surge load which is important for a off grid load. Depending on your application you can run the pump at lower output speed which will reduce pump cycling. Most new household pump applications are variable speed pumps that vary speed to maintain flow rather than using a pressure tank.
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