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Thread: Queen City comes to life! After a fight

  1. #1
    Join Date
    Oct 2006
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    Queen City comes to life! After a fight

    Been watching for a decent deal on a VFD for the Queen City grinder. I found one on Ebay that went in my price range. It was an older model and listed as obsolete by the manufacturer. In my book it is not obsolete till it doesn't work. Besides all I wanted was it convert the power to 3 phase. Anything else was a bonus.

    I was eating lunch and about to go spray some paint when the Post Lady came in the drive blowing her horn. New tool here, painting had to wait.

    Skim the manual, get the basics on the drive. It's better than I expected, it has options I didn't expect. Wiring is straight forward. Scrounge up a power cord and my 220V extension cords since I can not move the grinder by myself very far.

    15 minutes it's wired up. Plug up the cord and there is slight pop, a spark, a whiff of ozone and an adrenaline rush! The drive it humming very lightly. Everything looks good. So I push the toggle button to run and nothing....... Humm. Oh yea. The switch on the grinder! Turn it to on, hit run and thump, the grinder turns and then nothing. The overload relay on the unit tripped. Double check everything and try a few more times. Same thing. So I consult the manual. Sounds like a bad motor.


    Disconnect and check the motor leads. Everything looks good. But motors are not my strong point so I call Lane, he was an industrial electrician among many other trades. He tells me what I did was good and the motor sounded OK. But I needed to do one more check for a short. Bummer, it shows a small ground in the wiring. But never fear he says. Start taking it apart, the ground/short could be anywhere between the leads and motor. It's very small so look very close at everything!

    After finally figuring out how to get the old AB switch out without damage I start disconnecting leads and checking. Motor is good. So where is the short? Probably in this highly desirable and hard to find switch. After some searching I found it. Someone had wired the switch leads with hard copper wire. One of the leads had a bad spot in the insulation and appears it was grounding on the metal flex conduit.

    Good! More scrounging turns up an old extension cord that has donated it's organs to save a few machines in the Lab. So after 2 hours we have the problem fixed and rewired, ready to go. Hit run and thump. Same thing.


    More testing and everything is fine. Now I am beginning to doubt the drive is good. Dig into the manual and go through the trouble shooting steps. From the code the board gives me it is a current overload. The motor pulls 3.1 amps and the VFD is rated for 3.0 amps. I knew this but really didn't think .1 amps would cause a problem and besides it wouldn't draw that except under load. But maybe startup load is higher than I expected?

    The next step per the manual is to try adjusting the acceleration and deceleration times and setting the speed control to 20%. OK, find the switches on the board and slow everything down and hit the Run switch one more time.

    IT WORKED! I was amazed the grinder was actually working. It was making a funny high pitched noise but it was spinning. I turned the speed control up and more funny but different high pitched noises but it speed up. The noises are normal per the manual BTW. Only took 4+ hours!

    I tweaked the adjustments and got it set up like I wanted. The forward and reverse work. I was amazed that you could set the deceleration speed to stop with in probably 1 second. On coast it takes days to slow down.

    Now that I know it works, it's time to tear it down and clean and paint. Then find a place for her to live and install the permanent wiring.
    God grant me the senility to forget the people I never liked anyway,
    the good fortune to run into the ones I do,
    and the eyesight to tell the difference.


    Kudzu Craft Lightweight Skin on frame Kayaks.
    Custom built boats and Kits

  2. #2
    Alan DuBoff is offline Former Member (by the member's request)
    Join Date
    Nov 2006
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    711
    Oooohhh, ooooohhhh, aaaaahhhhhh....nice machine Jeff. That's gonna be one very nice grinder after you get it done.

    Can I ask, how much did you have to give for the VFD?

    I have an extra static phase converter, and I just picked up a 5HP 3 phase motor that doesn't appear to have been used, and was hoping I could build a DC with it. But I could use a VFD on that as well I 'spose. I imagine they go for $150-$200...

  3. #3
    Join Date
    Oct 2006
    Location
    The Heart of Dixie
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    Alan, you will be surprised. $26. No typo. Of course I paid $10 shipping I think it was.

    The reason it was cheap was it was rated at 3/4 hp and it is old larger wall mounted unit. I would never get a small one like I have on my lathe for that price. The older ones seem to go cheap and especially the smaller HP models. My motor is a 1 HP but the amp load is within my range so I feel safe with it. Plus it was a used unit. Even so it looks like new!
    God grant me the senility to forget the people I never liked anyway,
    the good fortune to run into the ones I do,
    and the eyesight to tell the difference.


    Kudzu Craft Lightweight Skin on frame Kayaks.
    Custom built boats and Kits

  4. #4
    Join Date
    Oct 2006
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    somewhere east of Queen Creek, AZ - South East of Phoenix
    Posts
    8,436
    Alan,
    I don't think you'll find a 1 phase input 3 phase output inverter at 5 HP. They sorta run out of steam at around 2 hp if I recall. The there all 3 phase in so unless your planning on using it along with your phase converter to give you adjustable speed you gonna be out of luck.


    Oh and Jeff, that a super find, the older inverters are a lot more forgiving IMHO.
    Last edited by Don Baer; 01-21-2007 at 08:35 PM.
    "There’s a lot of work being done today that doesn’t have any soul in it. The technique may be the utmost perfection, yet it is lifeless. It doesn’t have a soul. I hope my furniture has a soul to it." - Sam Maloof
    The Pessimist complains about the wind; The Optimist expects it to change;The Realist adjusts the sails.~ William Arthur Ward

  5. #5
    Alan DuBoff is offline Former Member (by the member's request)
    Join Date
    Nov 2006
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    711
    Don,

    I do have a static phase converter for the 5HP, which will leave me with about 3 1/2 HP, and that should probably be fine.

    Jeff, that's amazingly cheap! Do you get full power when using a VFD, or do you only get 2/3rd the rated HP?

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