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  1. #1
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    Default Yet another VFD post.

    Gday Everyone.
    I'm looking at getting a vfd to run my 3 phase mill on single phase. I've been doing a lot of reading here about these beasties and the more I read, the more confused I am becoming (that seems to happen a lot easier these days).
    I intend to replace the old, original two speed motor with a single speed 2.2Kw Teco motor that I have.
    My understanding is with the motor I have, when its configured in the Delta mode, it requires 220-240V three phase power. Is that correct?

    teco motor .jpg

    So would something like this be suitable for my motor?

    The other question I have is how do I work out what size 240v circuit do I need? 15A - 20A - 25A ?
    My son who is an eleco but lives interstate, is coming for a visit in a couple of months so I would like to get the cable run and have all the bits (for the dedicated circuit) ready for him to connect up.

    Any advise would be greatly appreciated.
    thanks in advance
    Peter

  2. #2
    BobL is online now Member: Blue and white apron brigade
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    Default

    The only reason for using more than 10A (usually 15A) GPO on a 3HP/2.2kW motor are the start up currents. If you program the VFD to have a slowish start (3 secs) you can run that motor via a VFD from a 10A GPO.

  3. #3
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    Default

    My understanding is with the motor I have, when its configured in the Delta mode, it requires 220-240V three phase power. Is that correct?
    Yes. A 3ph motor wired in Delta will only be supplied 240v from the 415v 3ph supply because of the way Delta works. A VFD will supply this 240v. This is why Delta motors are usually recommended.

    My lathe has a 7.5hp motor and the biggest current I have seen it draw is 12A and that was just when I was running it pretty fast while trying it out. It is also a 2 speed motor (Delta, YY), and works in both speeds via the VFD.

    Dean

  4. #4
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    Default

    Thanks for the info gents.

    That has reduced the cost a bit for me already as I already have a 16amp breaker and a 15 amp GPO.

    Do you have any thoughts as to the VFD I linked to?

    thanks
    peter

  5. #5
    BobL is online now Member: Blue and white apron brigade
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    Quote Originally Posted by bollie7 View Post
    Do you have any thoughts as to the VFD I linked to?
    I have 5 of those VFDs on machines in my shed. They are basic VFDs and should be fine for what you are doing.

  6. #6
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    Default

    Thanks for that Bob.
    Another question
    These are currently on ebay. They look very similar to the Huanyang one but slightly cheaper. (More than likely a different brand)
    The slight difference in price doesnt bother me but the ebay ones are listed from a seller here in Australia where as the Huanyang is in China.
    I'm wondering if you or anyone has had any problems with the Huanyang and if so how was it resolved from a warranty perspective?

    I'm just thinking its easier to return something to an Australian address than a China one.

    With the Huanyang unit I notice they say that they say that a braking unit is an optional extra. I dont envisage me wanting to use the machine for power tapping so is there any real need to have a braking facility? I know it might be nice to have, but essential - probably not.

    Thanks for your patience in answering my questions

    peter

  7. #7
    BobL is online now Member: Blue and white apron brigade
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    Quote Originally Posted by bollie7 View Post
    Thanks for that Bob.
    Another question
    These are currently on ebay. They look very similar to the Huanyang one but slightly cheaper. (More than likely a different brand)
    The slight difference in price doesnt bother me but the ebay ones are listed from a seller here in Australia where as the Huanyang is in China.
    I'm wondering if you or anyone has had any problems with the Huanyang and if so how was it resolved from a warranty perspective?

    I'm just thinking its easier to return something to an Australian address than a China one.

    With the Huanyang unit I notice they say that they say that a braking unit is an optional extra. I dont envisage me wanting to use the machine for power tapping so is there any real need to have a braking facility? I know it might be nice to have, but essential - probably not.

    Thanks for your patience in answering my questions

    peter
    They are the same unit but note they don't have a potentiometer to control speed - you would have to add that yourself.
    And the other ones come with an extension cord and remote control panel holder.
    All up it doesn't add up to a lot (i.e. <$10) but that depends how deft you are a basic electronics.

    I haven't had any problems with these so warranty hasn't come up yet.

    To add the braking unit is not a job for the faint hearted.

  8. #8
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    Thanks Bob.
    I'll probably go with the Huanyang then. Interestingly, only one pic of the Huanyang listing shows a potentiometer, all the others its not there.
    Thanks for your help.

    regards
    Peter

  9. #9
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    Default

    Those units run askpower firmware. They work fun, but they do have some quirks (e.g. if you set min freq too high it will trip on overcurrent).

    Most of the small units don't actually have the capacity to add an additional braking resistor, but the internal resistance will slow down a mill etc at quick enough for most.

    Note that most larger 415 motors don't have 240v delta windings, read the plate carefully.

    Lots of those 'AU' sellers (like the one I bought from) are in China anyway. Mine had china post labels.

  10. #10
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    Oh and when you run in single phase convert the output power to the current on the input side to get the equivalent capacity.

  11. #11
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    Default

    Ok. I've just ordered the Huanyang.
    Hopefully the delivery will be closer to the 10 day period than the 32 day.
    Then the fun will begin.

    peter

  12. #12
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    Default

    Quote Originally Posted by Pez View Post
    Oh and when you run in single phase convert the output power to the current on the input side to get the equivalent capacity.
    Pez, 1st off, Welcome to the forum.
    Can you add a bit more detail to what you said please? I dont understand what you mean. I know enough about electrics to know that I dont know much.

    thanks
    peter

  13. #13
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    Hi Peter

    Sorry - that was a terrible explanation! I've been a lurker for ages but posted from having the same struggle years ago. Not an expert but happy to share what I've learned.

    Basically the way the vfd's work is they put the line voltage through a rectifier and convert to DC. The DC charges some large capacitors, which creates the 'DC bus'.

    This is then fed into mosfets (think fancy silicon relays) that then switch on and off to make the three phase output.

    If you take the full load three phase current off the motor (e.g. 8.7A) multiplied by sqrt(3) that's your single phase input current.

    You'll only draw full load amps when you are really working it hard, so I wouldn't sweat an amp here or there.

    Some units that are 'single phase' models already have this derating but most don't. Just err on the side of larger - you'll get better filtering and larger capacitors out of it regardless.

  14. #14
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    Oh, and if you're planning on a dro use shielded cable - vfd's are really noisy electrically.

    Last tip - never ever unplug the load side with the inverter on. The feedback circuit will try to go to infinity and potentially let the smoke out.

  15. #15
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    Default

    Pez
    Thanks for the info.
    I'm removing the old 1.5Kw , 2 speed motor and replacing it with a single speed 2.2kw motor. (motor plate pic in my first post) It definately says 220-240V when in Delta mode.
    re the DRO & shielded cable. Do you mean shielded cable on the DRO or on the motor?

    thanks
    peter

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