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  1. #11
    i think if i look at it 2moro with a fresh head it'll be better.. but out of interest

    with Best Selling! Wantai Stepper Motor Driver DQ860MA 80V 7.8A 256Micro CNC Router Mill Cut Laser Engraving Grind Foam-in Motor Driver from Industry & Business on Aliexpress.com
    as my driver and Nema23 Stepper Motor 3.1Nm x 3 as motors where do i fall in to that table?

  2. #12
    Those drivers will accept up to 80V and the motors are fine with that, so you can use a 50V transformer since when rectified that will get approximately 50*1.41-1.1=69.6V. A 500VA transformer would be ideal for 3 of those motors.
    Old router build log here. New router build log here. Lathe build log here.
    Electric motorbike project here.

  3. #13
    Ok I think this is the kiddy....

    Standard Range Toroidal Transformers: CM2500450: 2500VA 230v to 4x50v

    But will it fit the bill????



    Rick
    Always bear in mind that your own resolution to succeed is more important than any other - Abe Lincoln

  4. #14
    How many machines are you planning on running?! That transformer is rated for 2500VA, so since 625VA is suitable for 4 motors, it could power 16!

    From that site this one would be the best option:
    Standard Range Toroidal Transformers: CM0625225: 625VA 230v to 2x25v
    If you're planning on adding a 4th axis then the 750VA isn't much more and would allow you to do that. It's better to get the 2x25V transformer rather and put the windings in series rather than 50V and put them in parallel since if the secondaries are in parallel some current will flow between them (and not into the load) due to manufacturing variations, which could be harmful if significant. It's not very likely though. Another option if you do have to use a 50V transformer is to not put them in parallel and keep 2 seperate circuits with 2 drivers on each.

    When you include postage and VAT this one is cheaper than airlink:
    Toroidal Transformer 625va 0 50v 0 50v
    Old router build log here. New router build log here. Lathe build log here.
    Electric motorbike project here.

  5. #15
    Quote Originally Posted by Jonathan View Post
    How many machines are you planning on running?! That transformer is rated for 2500VA, so since 625VA is suitable for 4 motors, it could power 16!

    From that site this one would be the best option:
    Standard Range Toroidal Transformers: CM0625225: 625VA 230v to 2x25v
    If you're planning on adding a 4th axis then the 750VA isn't much more and would allow you to do that. It's better to get the 2x25V transformer rather and put the windings in series rather than 50V and put them in parallel since if the secondaries are in parallel some current will flow between them (and not into the load) due to manufacturing variations, which could be harmful if significant. It's not very likely though. Another option if you do have to use a 50V transformer is to not put them in parallel and keep 2 seperate circuits with 2 drivers on each.

    When you include postage and VAT this one is cheaper than airlink:
    Toroidal Transformer 625va 0 50v 0 50v
    Ok i figure if i must build a supply then i would really build one, i will be running other things requiring voltages less than 50v so this should cover the lot.

    When i said i was going to do a "Big special" machine that is exactly what i meant.
    Although i am using 4 steppers in the design that will only be providing me with 3 Axis, this machine will be having a 4th with quite a few other gadgets, i was going to go for Din rail supplies so i could add more as and when i needed them, but it is very much easier to just add a din supply that build another power supply.

    So now i have opted to go down this road ive got to build in for the other stuff i will be fitting... Admittedly 2500va is a lot but i do like the 4x50v besides which its going to cost me more than that just to have the frame powder coated, as you may be becoming aware im building this thing for keeps...I may get a tad smaller transformer Ive got to do the math first.



    Rick
    Last edited by Ricardoco; 14-11-2012 at 03:50 PM.
    Always bear in mind that your own resolution to succeed is more important than any other - Abe Lincoln

  6. #16
    ok I decided on going for this one: Standard Range Toroidal Transformers: CM1200171: 1200VA 230v to 120v

    its not as big as the other one but then i Bought two!!

    I think they are adequate for the job at hand


    Rick
    Always bear in mind that your own resolution to succeed is more important than any other - Abe Lincoln

  7. #17
    Quote Originally Posted by Ricardoco View Post
    i will be running other things requiring voltages less than 50v so this should cover the lot.
    Then you should use the right size (750VA for 5 motors) transformer for the motors and get transformer(s) with lower voltage windings to power the lower voltage appliances, otherwise you've got to somehow drop the voltage further which is complicated to with any efficiency.

    Quote Originally Posted by Ricardoco View Post
    ok I decided on going for this one: Standard Range Toroidal Transformers: CM1200171: 1200VA 230v to 120v

    Er, I hope not as that has a 120V secondary not 50V or 25+25V which is what you need for the motors.


    Quote Originally Posted by Ricardoco View Post
    its not as big as the other one but then i Bought two!!

    So you'll have about 1.65kW surplus after powering the stepper motors - must be planning some pretty serious optional extras to use that much. Perhaps the machine is going to make tea...
    Old router build log here. New router build log here. Lathe build log here.
    Electric motorbike project here.

  8. #18
    Quote Originally Posted by Jonathan View Post

    Er, I hope not as that has a 120V secondary not 50V or 25+25V which is what you need for the motors.





    So you'll have about 1.65kW surplus after powering the stepper motors - must be planning some pretty serious optional extras to use that much. Perhaps the machine is going to make tea...
    Erm Not Sure what happened there here is the actual ones i have bought...

    CM1200424 - Standard Range Toroidal Transformers
    Product Description: 1200VA 230v to 4x24v

    Is that better???


    Rick
    Always bear in mind that your own resolution to succeed is more important than any other - Abe Lincoln

  9. #19
    Yes that's better, still seems OTT though. 4x25v would have been slightly better, but it's not a big deal.

    With that transformer you will be able to get multiples of 35V, so 70V for the motors and 35V for other things. What voltage do the other things require?
    Old router build log here. New router build log here. Lathe build log here.
    Electric motorbike project here.

  10. #20
    Quote Originally Posted by Jonathan View Post
    Yes that's better, still seems OTT though. 4x25v would have been slightly better, but it's not a big deal.

    With that transformer you will be able to get multiples of 35V, so 70V for the motors and 35V for other things. What voltage do the other things require?
    The other things range from 12v to 32v but the contactors can be what ever i want when i order them.
    Always bear in mind that your own resolution to succeed is more important than any other - Abe Lincoln

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