2kw step-up/step-down transformer + 220v "normal" vfd, or VFD w/ voltage doubler - Page 2


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Thread: 2kw step-up/step-down transformer + 220v "normal" vfd, or VFD w/ voltage doubler

  1. #21
    Community Moderator Al_The_Man's Avatar
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    Default Re: 2kw step-up/step-down transformer + 220v "normal" vfd, or VFD w/ voltage doubler

    Quote Originally Posted by austinatxr View Post
    My initial gut feeling though is that it is probably more sensible to do "typical" case-grounding everywhere, and re-reference the secondary to ground, so that the downstream's equipment assumptions of "referenced earth ground neutral" are maintained, rather than try to build a completely floating cart. I think this keeps things closer to "standard".
    .
    A good reference is NFPA79 Electrical Standards for Industrial Machinery.
    There is an older copy out there in PDF, if you need to get an idea.
    It has typical assembly methods and show control circuit wiring that conform to the NEC/CEC etc.
    In using any kind of GFCI you need a GND referenced Neutral.
    Al.

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    Default Re: 2kw step-up/step-down transformer + 220v "normal" vfd, or VFD w/ voltage doubler

    Quote Originally Posted by austinatxr View Post
    Also, i just had to share this little gem. Many people have talked about the spindles not being case-grounded. Well, it looks like I won the lottery! Is that, is that a ground wire attached I see? Awesome!

    but wait, is it screwed into plastic?!?!? Could they possibly have run a wire, and then somehow NOT gotten it to actually contact the case?

    VERDICT: The fluke says that the two are electrically connected. Continuity to the case is there.

    It does mean that the "ground" conductor is the screw itself, and not contact between the ring crimp and the case itself, since the plastic that the ring is sitting on is definitely NOT conductive. I feel that while valid, this is getting closer to nit-picking rather than more serious safety concerns. It is a definite attempt to move in a better direction. Someone will probably argue that a "bad" ground is worse than no ground at all, because it makes you think you are safe when you really aren't, but I think that this wire shows time, money and effort on the part of the manufacturer to try to do it better, and I think it is better to encourage safety efforts in the long run.

    Also, this model seems to feature o-rings for the water channels that go through to the rest of the motor, instead of just a tight fit and some sort of compound. Nice!

    It still has an "aviation connector" on the top though, I switched that out for a gland-end as recommended elsewhere on the forums. The gland end I got from mcmaster was a VERY nice fit. clearance fit for sure, but only about .010"-0.015" clearance or so, depending on where I measured.
    Some of the better spindle manufactures have the Ground connected, and that is a normal Ground point they use, they all have the Orings that is a fail if they did not have them, I have never seen one without Orings though

    Mactec54


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2kw step-up/step-down transformer + 220v "normal" vfd, or VFD w/ voltage doubler

2kw step-up/step-down transformer + 220v "normal" vfd, or VFD w/ voltage doubler

2kw step-up/step-down transformer + 220v "normal" vfd, or VFD w/ voltage doubler