SAG 12 VFD Conversion
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  1. #1
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    Mar 2021
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    Default SAG 12 VFD Conversion

    Hello there,

    I'm converting a SAG12 to to run off a VFD. I've got the motor rigged up to the VFD and running no problem. Now I'm trying to figure out how to get the DC clutches to work.

    I've attached a diagram. The red shows the stuff I think i can pull out (three phase power to motor). The blue lines are where i think I can wire up a 220volt singlephase input. Do I wire the live and neutral to each of the two phases that go to the transformer? Never worked with a transformer so might be completely confused.

    I can seperate off the coolant pump and sort that later so don't need to worry about that. Any advice on any other components that I can remove when running off VFD. sag12-schematic-vfd-change-.jpg

  2. #2
    Join Date
    Oct 2004
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    Hmmm.... I'm not personally familiar with the SAG12... is that chambered in 3" mag???

    Okay, so the diagram image is rather small, and it's got the common european 'mixed' single- and multi-line diagram character.

    I can't readily identify the clutches. I don't see a reversing contactor, so I'm guessing this is a constant-speed motor setup, with a f/n/r clutch system... if so, that's PROBABLY the area down in bottom left?

    Looks like (and you can probably see better) an aux contact in the original motor contactor,that might be providing power to the direction control switches which power the clutches... if so, that will need to be wired to an appropriate power source so that the clutching controls will work.

    The DC clutches are probably getting DC'd by virtue of the stack of diodes on the right, but I'd need a much bigger image in order to be certain.

    The transformer...same situation- too small for me to tell you for certain. Can you get a larger one posted?

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