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Thread: Wiring 3-phase Baldor motor to VFD

  1. #1
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    Wiring 3-phase Baldor motor to VFD

    So I have plans to use a VFD to control a Clearvue 3-phase dust collector. I thought I was good on wiring until I hit this page:

    https://www.electricaltechnology.org...-not-690v.html

    The confusion is between what is considered 208V 3-phase and 400V 3-phase. I have 230V single phase for input to the VFD. The Baldor motor has 9 wire leads coming out of it (T1 through T9). It can be wired for low voltage with T4-T5-T6 wired together or for high voltage with T1-T2-T3 wired together.

    Would someone help shed some light on this? Which wiring configuration should I be doing?
    Last edited by Aaron Inami; 08-02-2022 at 10:54 PM.

  2. #2
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    You should be wiring the motor for low voltage. The voltage from the VFD may be nominally higher but it will work without issue. Thousands of 3ph motors are wired for low voltage 3 phase and run on a 230v 1ph powered VFD without issues.
    Last edited by Michael Schuch; 08-03-2022 at 12:45 AM.

  3. #3
    I agree. A standard VFD does not increase the voltage on any one leg, so use the low voltage connections.

    However, you should advise which VFD you are using as I am told that there is an expensive vfd with a step-up transformer.

  4. #4
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    Thanks guys. I did more research last night and kind of came to the same conclusion, but I wanted at least a couple people chiming in here. My chosen VFD will be this ATO "single-phase to 3-phase" unit:

    https://www.ato.com/5hp-vfd

    Looking at the specs, it states that output voltage will be "3 phase AC 0~input voltage", which I interpret to mean output voltage will never be higher than the 220-230V input voltage.

    I came to the conclusion that I should wire the Baldor motor for low voltage when I discovered another section of ATO VFDs described as "220V to 380V VFD":

    https://www.ato.com/5-hp-vfd-1-phase...o-3-phase-380v

    These VFDs use single phase 220-240V for input but can output as much as 3-phase 460V. This unit is physically larger and heavier which lead me to think it has the step-up transformer that Greg was describing. That's the only way I can see being able to output higher voltage


    I also came across this page:

    https://vfds.com/blog/how-to-stop-vf...g-your-motors/

    It has the following quote in the section "(1) VFDs Damage Motor Windings":

    "Damaged motor windings problem is caused by extreme peak voltages. VFDs control motors with a simulated AC sine wave known as pulse width modulation (PWM). This process creates peak voltages high enough to break through motor insulation and short out windings."

    So, even though there are VFDs available which output high voltage at 380V-460V, it's apparent to me that we should use the lower voltage scenario as much as possible with VFDs to prevent motor winding damage. I think that if you need to run a motor at high voltage (460V), then you're better off with a rotary phase converter.
    Last edited by Aaron Inami; 08-03-2022 at 1:11 PM.

  5. #5
    Ah good, then you should be set. Baldor has plenty of online info on connecting their 9 wire motors.

    You no doubt have read elsewhere that if you get reverse rotation just swap over any two wires on the output side of the VFD to correct it.

    Greg

  6. #6
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    Quote Originally Posted by Greg Quenneville View Post
    You no doubt have read elsewhere that if you get reverse rotation just swap over any two wires on the output side of the VFD to correct it.
    Ah, no I had not read that. I assumed that I would just set the VFD parameter to reverse direction if I needed it, but the 2-wire swap is an easier fix.

  7. #7
    Indeed you can select reverse rotation on the VFD control panel, but the units I have used default to FWD when power is cycled. One less thing to forget.

    For three years now every time I use my bandsaw I keep reminding myself to swap those leads over. One day.

  8. #8
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    Same with me, Greg. I remember to start it in reverse most of the time.

    I'm in the process of upgrading all my HVAC tools to the Fieldpiece brand. Looking over their clamp meters, they have one that the short description says has a function that will tell you which wire is which in a 3 phase motor. Don't ask me how it does that because I have no idea, yet. So far, I don't think we have any variable speed fans, but it's not that much more than the model below it, so I might as well be well prepared for some future upgrade.

  9. #9
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    I tried for a long time to get CV to put DOR stickers on the fan housing and finished up making my own. They may be adding them these days but you can quickly tell if the DOR is wrong because the cyclone will make a whistling sound but still pump air though not as much when the DOR is correct. I guess CV never saw the point of the DOR sticker because the vast majority of their domestic sales was single phase machines and most probably still is. Using a VFD takes away the limit of starts that single phase machines have.
    Chris

    Everything I like is either illegal, immoral or fattening

  10. #10
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    I've got a DOR sticker on my new Clearvue EF5 metal cyclone. It will definitely help once I get it up and running (still waiting on filters). I don't know if they are doing this on their plastic cyclones.
    EF5_DOR_sticker.jpg

  11. #11
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    I guess they were forced into it with the metal cyclone.
    Chris

    Everything I like is either illegal, immoral or fattening

  12. #12
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    Quote Originally Posted by Chris Parks View Post
    I tried for a long time to get CV to put DOR stickers on the fan housing and finished up making my own. They may be adding them these days but you can quickly tell if the DOR is wrong because the cyclone will make a whistling sound but still pump air though not as much when the DOR is correct. I guess CV never saw the point of the DOR sticker because the vast majority of their domestic sales was single phase machines and most probably still is. Using a VFD takes away the limit of starts that single phase machines have.
    That seems like a worthwhile feature on a cyclone. The less time noise producers have to run the better.

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