Phase converter

  1. Troy Member

    Messages:
    65
    Location:
    Sheffield England
    Finally got round to finishing the build. Of my rotary converter
    Using step up transformers
    And a 15hp idler motor
    Quiet supposed it only pulls 21 odd amps not underload will get some better pictures later
    It started as a purchase of a converter in bits not working for £100
    Then a new enclosure, new contactors and switch gear
    The three holes are now filled with illuminated phase indicator lights
    Its wired pretty straight forward with a contactor up front and a cap contactor to fetch the starting caps in and I've added a phase detection relay wired to an on delay timer to hold the output contactor off for 5 or so seconds till it has all three phases and the idler is up to speed

    Total cost was around 260
    100 for the original pile of bits
    50 for the cabinet
    110 for contactors contectors lights ect


    Troy
     
    • IMG_20200218_163545.jpg
    indy4x, Retired, minimutly and 8 others like this.
  2. Troy Member

    Messages:
    65
    Location:
    Sheffield England
    Updated pictures as promised
    Not the neatest inside tbh but it works
     
    • IMG_20200402_082013.jpg
    • IMG_20200402_082037.jpg
    johnny max, magnet, Retired and 5 others like this.
  3. 123hotchef Member

    Messages:
    9,678
    Location:
    Kent
    good job
     
    Troy likes this.
  4. MBB Forum Supporter

    Messages:
    1,070
    Location:
    northumberland
    The transformers look small for 15 hp.
     
  5. Troy Member

    Messages:
    65
    Location:
    Sheffield England
    I have three more but haven't fitted them as I don't need them tbh
    I've had an 11kw motor and hydpump running on it it under some load but cudnt load it any more u fortunely it ran sweet
     
    MBB likes this.
  6. steviec_lj

    steviec_lj Rust Welding Professional

    Messages:
    2,715
    Location:
    Barnetby, N.Lincs
    Looks fantastic..

    Now what you need to do is a “Dummies Guide”, so folk like me can follow it, a little each weekend.

    Ive probably got all the bits to make one, I loath getting rid of anything.
     
  7. Troy Member

    Messages:
    65
    Location:
    Sheffield England
    Before I started this I did a lot of reading but it didn't sink in tbh, i found working it out as I went along much easier I just did it logically and got it to work basic barebones with contactors operated manually
    Then did a simple temp switchs to operate contactors
    Re did that properly
    Then added the extra bits phase detection, time delayed output
    I have have the bits and a 7.5hp idler motor to make another when I get the rest of the bits and some time I'll do I'll do a video step by step
     
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  8. Hopefuldave Intergalactic pot-mender

    Messages:
    1,705
    Location:
    The Shed of Danger, surrey, England
    Should I post my all-the-bells-and-whistles wiring diagrams?

    Dave H. (the other one)
     
    Seadog and Troy like this.
  9. Agroshield Member

    Messages:
    1,043
    I hope this is not being rude but is the 21 amps correct or a typo.? If it is this high, what does it pull when it is driving a machine? What supply/breaker/plug are you running it off? Thanks.
     
  10. Hopefuldave Intergalactic pot-mender

    Messages:
    1,705
    Location:
    The Shed of Danger, surrey, England
    It's possibly a power factor thing - mine pulls a lot of apparent amps with just the transformer connected, then when the motor connects (on the far side of the transformer) the apparent current/power drops as the balancing capacitors correct the power factor closer to unity and put the voltage and current closer in phase - they add a leading current to the lagging current in the transformer inductance.

    I'm running mine (9 KVA transformer, 10 HP in motors) hardwired through a 63A isolator from a 40 amp type D MCB, there's also a 30mA RCD upstream of it, fine unless English Weather gets in the transformer (again)... Today's task is to get it in the SoD and dry it out :( Then a doghouse to keep the weather out!

    Dave H. (the other one)
     
  11. Troy Member

    Messages:
    65
    Location:
    Sheffield England
    21 is correct no load
    With a big bench grinder under load around 25ish amps
    And 7. 5hp motor under load around 33 amps ish

    Its hardwired back to the board fed from a 40amp ctype mcb
     
  12. steviec_lj

    steviec_lj Rust Welding Professional

    Messages:
    2,715
    Location:
    Barnetby, N.Lincs
    Yes please, the other Dave.

    You wouldn’t believe how badly I retain information, I have to write everything down as it comes to mind otherwise it’s lost, forever!
     
  13. Agroshield Member

    Messages:
    1,043
    Thanks for the info. So how does power factor relate to running cost? Big Clive always mentions it in his videos. I am not sure if we are currently(!) charged according to power factor or whether it is a feature that could be done with a smart meter should the electricity company decide to do so. Any insights appreciated.
     
  14. Hopefuldave Intergalactic pot-mender

    Messages:
    1,705
    Location:
    The Shed of Danger, surrey, England
    Hope they make sense, quick summary but happy to answer questions!:

    9 KVA transformer is an old oil-cooled welder with the welding winding stripped off and a new winding on a 3D-printed bobbin.
    Otherwise a pretty standard Fitch converter, once past the transformer. No balance (or start) capacitor values as they depend a lot on the motor, load etc, a bit suck-it-and-see!

    Control plane has long-arm microswitches for the fault indicators / disable, bolted onto DIN rail spacers, levers on MCBs and RCD drilled through at the tips (they often have a convenient almost-through hole in the moulding) and a bit of rod to trip the microswitches.
    Switches and aux contacts are arranged to force a sequence of power to transformer, then motor, finally load, s that initial surges are separated in time (less chance of popping the RCD or MCB feeding the whole mess!) - so three (illuminated, cheap on EvilBay) on/off switches operated in sequence to power up (the motor start switch operated the start relay ONLY while the button's pushed, but latches the motor relay - via the control relay).

    Dave H. (the other one)
     
  15. Hopefuldave Intergalactic pot-mender

    Messages:
    1,705
    Location:
    The Shed of Danger, surrey, England
    A pic of it "under construction" - a bit OTT, maybe...
    (Start capacitors are in the box, balance caps live outside in their own IP66 plastic box next to the motor).

    Dave H. (the other one)
     
    • RPC front panel.jpg
  16. Seadog

    Seadog Forum Supporter

    Messages:
    6,568
    Location:
    NE London - UK

    My lash-up using a 4kW motor draws around 34A at start-up which reduces to 2A at idle. Anyone with a H&S hat on, don't watch :D

     
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  17. maz0

    maz0 Forum Supporter

    Messages:
    646
    Location:
    Central Scotland
    I'll be trying my hand at a pony motor version in the next few weeks, now that I have power in my shed. Just need to build a contraption to spin up then de-couple when its up to speed.
     
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  18. Seadog

    Seadog Forum Supporter

    Messages:
    6,568
    Location:
    NE London - UK
    How large is the motor you're going to spin up?
     
  19. Hopefuldave Intergalactic pot-mender

    Messages:
    1,705
    Location:
    The Shed of Danger, surrey, England
    Are you using a HUGE motor? If not, it's easy to do the cap-start version, just and extra contactor and a big start cap or two.
    Cleverest pony-start I've seen used the clutch off a car aircon compressor, but needed a 12v DC supply, simplest I've seen was the pony motor on a board with a rope to lift it and put tension on the belt :)

    Dave H. (the other one)
     
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  20. maz0

    maz0 Forum Supporter

    Messages:
    646
    Location:
    Central Scotland
    7.5 HP so not that big to be honest, but I feel more confident getting a pony system to work than mucking about with capacitors for the start up part.
     
    Seadog likes this.
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