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Thread: Wide belt phase convertor

  1. #1
    Join Date
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    Southwest WI
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    Wide belt phase convertor

    I purchased a scm wide belt about a year ago now and its been in storage since I picked it up. I had intended on getting 3 phase power in my new shop but the price for the electrical company and my electrician was 114k just to get the panel installed. My next idea was a rotary phase convertor. I called up American rotary and the price for the convertor they recommended was around 8k. I'm now thinking about a large vfd since I have several other vfds in my shop and they work well. The wide belt has a 18hp main motor and 2 separate 1 hp motors for the feed belt and table height adjustment. Has anyone used a vfd for a wide belt or possibly a digital phase convertor like the phase perfect?

  2. #2
    Join Date
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    Building a rotary phase converter isn't that difficult. You would need and idler motor about 1.5x the hp of your biggest motor... so 27hp or bigger. I built my 10hp idler RPC ~25+ years ago and it has been very handy. The larger RPC's I have worked with have used a pony motor to start the main idler motor instead of start capacitors.

    Most of my 3ph tools are on VFD's now but my largest VFD is only a 7.5hp. Most of the VFD's I have seen of the size you need all call for 3 phase power input. I don't know if the diodes in the 3ph rectifier on the big VFD's are over sized enough to handle using only 4 of the 6 diodes in the 3ph rectifier to produce the needed DC without overloading those diodes. Often the bigger VFD's will have terminals for direct connection to the DC bus so you can use and external rectifier instead of the one built into the VFD. A VFD should be used to only run a single motor, so you would need the big VFD for the 18hp motor and a couple 1hp VFD's for the two 1hp motors. VFD's were not originally designed with the intent of generating 3phase out of 1 phase. There original purpose was for speed control of 3ph motors on a 3ph supply. The phase convertor functionality of VFD's is just a REALLY happy side effect of there original functionality. You will be in for some rewiring of the original controls if you go with 3 VFDs. I think this is an area where a RPC might be the cheapest route.

    The phase perfect looks like a fixed frequency VFD. They look like nice units, how much do they cost for the size you need? VFD's were not originally designed with the intent of generating 3phase out of 1 phase.
    Last edited by Michael Schuch; 01-08-2022 at 3:48 AM.

  3. #3
    Join Date
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    I had a large widebelt that I ran off a 'static' phase convertor for a few years. Ironically I just sold that converter (for $100), it was rated at 10-18hp.

    The static converter 'derates' - I have read assume 2/3 power level. Fine, it was still plenty to handle anything I put through it.

  4. #4
    I think a VFD is a non-starter. You'd have to find a 20HP VFD that supports enough input current to allow it to run on a single-phase input, which has Michael said, probably doesn't exist. Plus you can only run 1 motor per VFD, so you'd need to figure out what to do with the two smaller motors (either separate VFDs or change them to single-phase motors). Then all the widebelt controls need to be bypassed to allow the VFD to be directly connected to the motor.

    A Phase Perfect might be a good option at ~$5k. But an RPC would likely be cheapest. They are not difficult to build if you can source an appropriate motor.

  5. #5
    Quote Originally Posted by Mitch schiffer View Post
    Has anyone used a vfd for a wide belt or possibly a digital phase convertor like the phase perfect?
    Yes on the Phase Perfect. Also, yes to American Rotary as well as Kay Industries.

    Erik

    DF05053A-06B7-496D-A72C-ABEB99CD6008.jpg
    Ex-SCM and Felder rep

  6. #6
    You should be able to get a Phase perfect 20hp for less. From what Ive been told by Erik Loza (Felder) and my SCM rep, VFDs arent ideal choices due to the poor waveform. Go rotary or something like a phase Perfect.

  7. #7
    Speak of the Devil. ��

  8. #8
    Join Date
    Jan 2010
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    Tampa Bay, FL
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    I use a Phase Perfect on mine. Works great. No issues.
    - Its not that Im so smart, its just that I stay with problems longer. Albert Einstein
    - Welcome to Florida. Where the old folks visit their parents

  9. #9
    Quote Originally Posted by derek labian View Post
    Speak of the Devil. ��
    I resemble that remark

    Erik
    Ex-SCM and Felder rep

  10. #10
    You'll need a 40hp RPC to run that wide belt machine properly. You can link 2 20hp RPC's together to do it.
    "Anything seems possible when you don't know what you're doing."

  11. #11
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    I believe that is what American rotary had quoted me as well. I was hoping to find a lower cost option. It seems like a 40hp vfd would work and I can get one for cheap or free from my previous coworkers in the industrial maintenance field, however that doesn't seem to be a popular route to go. I'm now thinking i will end up with a phase perfect.

  12. #12
    You can get a 60hp RPC panel only for under a $1,000 and then just add a used 60hp 3 phase electric motor. You can get 60hp 3 phase motors for $600 or so dollars if you are patient and look locally.

  13. #13
    Static converters only start a 3 phase motor, then they just single phase, which is the reason why 1/3 of the HP is lost when using a static phase converter.

  14. #14
    Quote Originally Posted by Rollie Meyers View Post
    Static converters only start a 3 phase motor, then they just single phase, which is the reason why 1/3 of the HP is lost when using a static phase converter.
    Rollie, is that correct? I have several customers running entire shops full of 3-phase industrial equipment off static phase converters.

    Erik
    Ex-SCM and Felder rep

  15. #15
    Quote Originally Posted by Erik Loza View Post
    Rollie, is that correct? I have several customers running entire shops full of 3-phase industrial equipment off static phase converters.

    Erik
    It's true. Those machines are running hot and at ~2/3 power.
    "Anything seems possible when you don't know what you're doing."

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