240 volt single phase input VFD's with 380/440 three phase outputs
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    Default 240 volt single phase input VFD's with 380/440 three phase outputs

    Hello all,

    I am looking for the best way to power a 0.5hp two speed 380/420V 3 phase motor from a BCA Jig Borer. It is in my home shop so I only have access to domestic 240V single phase power (I'm in the UK)

    I have been looking at rotary phase converters, which seem like a good option as an investment for the work shop albeit a costly one.

    I have also come across these Voltage stepper VFDs from China and wondered if anyone can advise on them?

    step up boost converter inverter 220v to 380v 3 phase power transformer for motor VFD|Inverters & Converters| - AliExpress

    The BCA has a speed selector which changes the motor from delta (for low speed) to star (for high speed) so would I be able to use one of the above step up VFD's to power the motor if I kept it in the high speed setting?

    Thanks for any advice, I still have very limited knowledge of these kind of things!

    Matt

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    you need the same input voltage as you require for output on a vfd.. AKA you need a transformer to step it up.

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    Quote Originally Posted by dr_dvice View Post
    Hello all,

    I am looking for the best way to power a 0.5hp two speed 380/420V 3 phase motor from a BCA Jig Borer. It is in my home shop so I only have access to domestic 240V single phase power (I'm in the UK)

    I have been looking at rotary phase converters, which seem like a good option as an investment for the work shop albeit a costly one.

    I have also come across these Voltage stepper VFDs from China and wondered if anyone can advise on them?

    step up boost converter inverter 220v to 380v 3 phase power transformer for motor VFD|Inverters & Converters| - AliExpress

    The BCA has a speed selector which changes the motor from delta (for low speed) to star (for high speed) so would I be able to use one of the above step up VFD's to power the motor if I kept it in the high speed setting?

    Thanks for any advice, I still have very limited knowledge of these kind of things!

    Matt
    Two speed motors are usually the same voltage for both speeds.

    As for the voltage converter vfds, they are a simple voltage doubling rectifier, same as what is in most older computer power supplies, a single switch alternates between 120/240v operation, with the capacitors running at 340volts in both cases. (in this case its a 240v doubler so more like 680volts dc)

    Personally I would take the risk to buy the vfd you linked to, or something similar, buy at least a 1hp rated drive, so you have a 50% derate.

    you can also take an old 480vac AB 1305 drive, and connect your 240v line in, to all 3 phases on the terminal block, and the other wire goes to the mid point of the two 400 volt capacitors which are in series. You have then made a voltage doubler and the drive will run. you will need to derate it on the order of 30%. A 2hp drive would operate a 1/2hp motor just fine without overheating the capacitors.

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    There are devices called "boost converters" that can step up your voltage. They are used extensively in the small VFDs that accept 120V single phase input and allow you to run a 230V 3 phase motor. In the Chinese unit you linked to, they are using the same technique to boost 220V single phase to 380V 3 phase. But...

    1) 99% of the stuff you see on sites like AllieExpress related to VFDs is off-brand Chinese crap, not worth the electrons used to display them on your screen. To paraphrase an old saying, "I wouldn't touch that wilt someone else's PC..."

    2) The reason why it doesn't exist (230 in, 460 out) is because in order to boost to 460V, the components used inside of the boost converter get to be so expensive that it's less expensive to just buy a transformer to go ahead of the drive to step up from 240 to 480V first, then use a 480V rated drive that can accept single phase input (most can now).

    Just do it that way, it's simpler, cleaner, more reliable and less expensive.

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    Thank you for your replies.
    I think I will hold off for now and either wait for a second hand RPC to turn up in the New Year or just fit a more modern dual voltage three phase motor and a normal VFD.

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    Compare the prices of a rotary converter and a 240V in, 415V out inverter from DrivesDirect.

    I've currently got a 7hp version of the drivesdirect box and so far it's going well. They modify standard, decent quality VFDs, but they do guarantee the end product.

    I'd be leary of a static converter...

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    I have one of these 240-415V VFD converters somewhere between here and China. I am going to use it to run my 10EE.

    It is going to be a wild Rube Goldberg device for sure. A 240V input converted to 415V, powering an AC motor, that runs two DC generators that run a 3hp DC motor.

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    The voltage doublers aren't any special sauce. All they need to do is use two banks of capacitors in series - I think most drives already do this as 800V-rated caps aren't super common. Then it's just one extra copper link.

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    Quote Originally Posted by dr_dvice View Post
    Hello all,

    I am looking for the best way to power a 0.5hp two speed 380/420V 3 phase motor from a BCA Jig Borer. It is in my home shop so I only have access to domestic 240V single phase power (I'm in the UK)

    I have been looking at rotary phase converters, which seem like a good option as an investment for the work shop albeit a costly one.

    I have also come across these Voltage stepper VFDs from China and wondered if anyone can advise on them?

    step up boost converter inverter 220v to 380v 3 phase power transformer for motor VFD|Inverters & Converters| - AliExpress

    The BCA has a speed selector which changes the motor from delta (for low speed) to star (for high speed) so would I be able to use one of the above step up VFD's to power the motor if I kept it in the high speed setting?

    Thanks for any advice, I still have very limited knowledge of these kind of things!

    Matt
    cheek this video out on youtube he is also in the uk it may be a bit more then you want but i am sure it can be scaled back a bit

    Rotary phase converter - UK - Part 1, Intro. - YouTube

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    Quote Originally Posted by dr_dvice View Post
    Thank you for your replies.
    I think I will hold off for now and either wait for a second hand RPC to turn up in the New Year or just fit a more modern dual voltage three phase motor and a normal VFD.
    For a jig borer, that's exactly what I would do... fit a common motor type, and use a VFD. I'd yank the motor's mechanical cooling fan and put a constant-speed fan on it in the process.

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    I'm in much the same boat (actually why I signed up in the first place), trying to run an old Monarch lathe wired for 550v Delta off of 240v shop power.

    So far, I've seen my options to be:

    1) Sketchy import VFDs rectifying 240 to 338, which still derates the motor.
    2) Single phase 240/480 transformer fed into a proper 480 VFD, expensive for me because I need 15kva
    3) Same as above with a rotary phase converter instead
    4) Replace the motor outright

    For your 0.5hp motor, option 2 might work well, you'd need only a 400VA transformer (assuming I did that math right). The ones I've seen on ebay are in the $200 range, not sure what the UK market looks like, plus a couple hundred more for a cheap 1hp 480v VFD.

    Personally, I'm closer to option 4, as a 15kva transformer would run me more than I paid for the lathe.

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    Quote Originally Posted by kc1lso View Post
    I'm in much the same boat (actually why I signed up in the first place), trying to run an old Monarch lathe wired for 550v Delta off of 240v shop power.


    John... which Monarch are you trying to run?

    de KW0d

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    FYI normal VFDs recify 240VAC into ~340VDC, then produce 240VAC again. This is because the rectified voltage is the peak voltage while the AC voltage is the RMS.

    A voltage doubling VFD will get you about 480VAC out, with a DC link at around 640V-ish. This is much closer to your input design voltage, and will get you full torque up to about 85% speed.


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