Thoughts on VFD use (Variable Frequency Drive) are they worth it
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  1. #1
    Join Date
    Sep 2018
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    Houston, TX
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    Thoughts on VFD use (Variable Frequency Drive) are they worth it

    I was looking at the benefit of having a VFD drive to run a 3 phase Hobart welder.
    I am looking for insight in to Converting welder to single phase or buying a VFD --- any thoughts will be appreciated.
    New to welding
    Always willing to learn something new!

    Miller Thunderbolt XL

  2. #2
    Join Date
    Mar 2017
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    bar stool
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    Re: Thoughts on VFD use (Variable Frequency Drive) are they worth it

    If you're talking about a transformer welder it WON'T work.
    A 3Ř rectifier is completely different from a single Ř rectifier.
    Cost of a VFD to power a transformer machine would be killer as well.

    On a motor driven machine you can buy one hell of a lot of welder for what the VFD will cost you.

  3. #3
    Join Date
    Nov 2012
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    871

    Re: Thoughts on VFD use (Variable Frequency Drive) are they worth it

    You'd never get enough current on single phase power to run a 3 phase welder, even IF the VFD was 100% efficient and they aren't. Also a large VFD what be horribly expensive. It would be cheaper to just buy a new single phase welder.

    FWIW there are a few 3 phase welders that will run off of single phase power but usually they just disconnect two of the three transformers inside of the welder which means that the welder can only deliver 1/3 of the power that it's rated for. So yes, it will work but it probably won't have enough power to be practical.

  4. #4
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    Sep 2018
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    Houston, TX
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    Re: Thoughts on VFD use (Variable Frequency Drive) are they worth it

    Thanks for the feedback - The metal plate indicates 230/460 amps so I need to pull the cover and see if there is a way to switch it easily or another adjustment with the transformers and adding capacitors.
    New to welding
    Always willing to learn something new!

    Miller Thunderbolt XL

  5. #5
    Join Date
    Aug 2010
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    West Central Ohio
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    104

    Re: Thoughts on VFD use (Variable Frequency Drive) are they worth it

    Maybe if you post the model no. of your welder someone could help with converting it.
    Hobart Beta-Mig 250
    T-D Cutmaster 81
    Miller Maxstar 150STL
    Miller T-Bolt 225 AC
    Chicago Electric Mig 151
    Hobart RC-256 Haas-Kamp Conversion(sold)

  6. #6
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    Dec 2014
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    Wasilla, Alaska
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    128

    Re: Thoughts on VFD use (Variable Frequency Drive) are they worth it

    There are several threads on the net describing conversion of three phase welders to single phase. IIRC most of them are for Miller/Hobart, Good luck!

  7. #7
    Join Date
    Mar 2014
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    328

    Re: Thoughts on VFD use (Variable Frequency Drive) are they worth it

    Google "Haas Kamp conversion" and then read to your heart's content. Just asking out of curiosity but what've you got? Maybe an old RC-301?
    Last edited by AGW; 10-05-2018 at 11:15 PM.

  8. #8
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    Re: Thoughts on VFD use (Variable Frequency Drive) are they worth it

    Quote Originally Posted by AGW View Post
    Google "Haas Kamp conversion" and then read to your heart's content. Just asking out of curiosity but what've you got? Maybe an old RC-301?
    Any member of that cult posted a scope trace of the arc wave form from that mutilated contraption?

  9. #9

    Re: Thoughts on VFD use (Variable Frequency Drive) are they worth it

    I would look at phase converter
    They are simple build, low in cost and give ture three phase

    VDF is like any other electronic it has short life spand
    It for changing the speed motors

    Dave

    Quote Originally Posted by DieselHutch View Post
    I was looking at the benefit of having a VFD drive to run a 3 phase Hobart welder.
    I am looking for insight in to Converting welder to single phase or buying a VFD --- any thoughts will be appreciated.
    HF 170 welder
    HF 4x6 band saw
    South Bend 9N
    Mill
    B&D mag drill
    Victor torch

  10. #10
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    Sep 2018
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    Houston, TX
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    Re: Thoughts on VFD use (Variable Frequency Drive) are they worth it

    Model - Hobart RC -200
    Amps - 200
    Max OCV 35
    % Duty cycle 100
    Volts. 230/460
    Phase 3 HZ. 60

    Spec. 6430-1
    Last edited by DieselHutch; 10-07-2018 at 12:50 PM. Reason: Trying to add photos

  11. #11
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    Aug 2010
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    West Central Ohio
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    Re: Thoughts on VFD use (Variable Frequency Drive) are they worth it

    You can check this out. I don't know if this fellow ever got his working but it should get you started.https://www.practicalmachinist.com/v...=hobart+rc-200
    Or this one:https://www.practicalmachinist.com/v...-200-a-301715/
    Good luck.
    Hobart Beta-Mig 250
    T-D Cutmaster 81
    Miller Maxstar 150STL
    Miller T-Bolt 225 AC
    Chicago Electric Mig 151
    Hobart RC-256 Haas-Kamp Conversion(sold)

  12. #12
    Join Date
    Sep 2018
    Location
    Houston, TX
    Posts
    6

    Re: Thoughts on VFD use (Variable Frequency Drive) are they worth it

    Thanks all for the input.
    New to welding
    Always willing to learn something new!

    Miller Thunderbolt XL

  13. #13
    Join Date
    Sep 2018
    Location
    Houston, TX
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    6

    Re: Thoughts on VFD use (Variable Frequency Drive) are they worth it

    I ended up building a 3 phase converter to power my 3 phase Hobart RC -200 mig welder with a Hobart 19 wire feeder.

    15 hp motor, start capacitor, 8 run capacitors.

    Sounds like bacon frying. I still need practice working on the argon flow, wire speed and current.

    Any comments on fine tuning are much appreciated.
    Last edited by DieselHutch; 04-09-2019 at 02:42 AM. Reason: Following up

  14. #14
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    Oct 2018
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    Sunny Florida, Orlando.
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    Re: Thoughts on VFD use (Variable Frequency Drive) are they worth it

    I assume you got this cheap because it is 3 phase.
    Now there is a whole world of under-priced tools available as a side benefit of the RPC.
    Hit Craiglist for that 7.5hp 3 phase table saw, plasma cutter, Bridgeport, monster compressor for sandblasting, mega grinder, etc.

    Glad your welder works.

    EDIT
    yes vfd can be "worth it" on certain machines, but it's meant to be a speed control/converter. Wrong application.
    Last edited by BananasCentral; 04-09-2019 at 07:47 AM. Reason: op
    If you are selling a lathe that swings 22", and live in Central FL, please PM me a price and some pics.

  15. #15

    Re: Thoughts on VFD use (Variable Frequency Drive) are they worth it

    Quote Originally Posted by FlaJoe View Post
    FWIW there are a few 3 phase welders that will run off of single phase power but usually they just disconnect two of the three transformers inside of the welder which means that the welder can only deliver 1/3 of the power that it's rated for. So yes, it will work but it probably won't have enough power to be practical.

    Properly designed 1/3 phase machines are more efficient on 3 phase. The output is often identical or close but usually not going to cut it back to 33% capacity.
    Attached Images Attached Images  

  16. #16
    Join Date
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    3,940

    Re: Thoughts on VFD use (Variable Frequency Drive) are they worth it

    Properly designed 1/3 phase machines are more efficient on 3 phase


    Properly designed would mean the single/three phase output duty-cycle would the same. (IMO) single phase input amps are more..I can get 300 amps, 28 volts out of my LM-200, running off a 15 hp RFC I have. It's more efficient running on single phase input without the rotary making the three phase leg....
    Esab 2200i-TA34
    Esab 160i caddy
    Thermal Arc LM-200 Lincoln feeders
    Thermal Arc Pee-Wee 85s
    Thermal 60i (Beast)
    Klutch P-300i/ 120 volt Plasma.












    If I agreed with you, we'd both be wrong!

  17. #17
    Join Date
    Oct 2014
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    419

    Re: Thoughts on VFD use (Variable Frequency Drive) are they worth it

    Quote Originally Posted by Brand X View Post
    Properly designed 1/3 phase machines are more efficient on 3 phase


    Properly designed would mean the single/three phase output duty-cycle would the same. (IMO) single phase input amps are more..I can get 300 amps, 28 volts out of my LM-200, running off a 15 hp RFC I have. It's more efficient running on single phase input without the rotary making the three phase leg....
    I hope so.
    That was my point that the 1/3 phase units don't loose 2/3's of there power running on single phase.

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