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IndustryArena Forum > WoodWorking Machines > DIY CNC Router Table Machines > 1st Build, will this be a decent Design?
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  1. #73
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    Re: 1st Build, will this be a decent Design?

    The electrical ampacity ratings of wire are based on a number of things including the temperature rating of the insulation. If you are in an area where the NEC applies acceptable current ratings can be defined in the code (for specific usage). Transformers are an interesting discussion but I think I’d side with others and have to question the wisdom of 18ga wire in a secondary operating at greater than 15

    The reality is comments from a transformer designer / engineer would shed more light on the issue. The other problem here is the fact that far too many online sellers have no idea what they are selling. The 18 ga could easily be the primary.
    Quote Originally Posted by __Britt View Post
    Disclaimer: I am not an electrical engineer; nor do I play one on TV.

    Well, FWIW there is this:

    https://www.powerstream.com/Wire_Size.htm

    At 56v, 1000 watts is about 17.9... lets call it 18 amps.

    18ga wire, according to that chart, should be good up to about 16 amps in free air; but only 2.3 amps in a bundle... this leads me to thinking that the wire in question is a bit on the light side for the task at hand. On the other hand; I often see transformers wound with lighter gauge wire than what is feeding them, so... ???

  2. #74
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    Re: 1st Build, will this be a decent Design?

    The other problem here is the fact that far too many online sellers have no idea what they are selling. The 18 ga could easily be the primary.
    The Great Internet Giveth, and the Great Internet Taketh Away... (low prices, and competency, respectively, in this case).

    18 on the primary would tend to make more sense...

    I wonder if dropping a line to Antek might be enlightening... they do manufacture torroidial transformers from scratch, so... ???

  3. #75
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    Re: 1st Build, will this be a decent Design?

    I do not understand where the problem is. A toroidal transfomer of 1kW capacity and 10 or 20 A output at 50+ V is an off-the-shelf item in America. Also in Europe and elsewhere. Retailers have them. What's more, several mfrs will wind a transformer (eg 1 kW) to your specs. Just Search.

    There are lots of them on eBay too, although you will have to crawl through the listings in most cases to get the actual specs.

    Cheers
    Roger

  4. #76

    Re: 1st Build, will this be a decent Design?

    So I've found this and from what people have said I think it will be suitable, does anyone have any thoughts before a go ahead and buy it... - https://uk.farnell.com/multicomp/vtx...P_LastViewed_1

  5. #77
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    Re: 1st Build, will this be a decent Design?

    It's a fine toroidal transformer, but at 40V it might leave your motors a bit slow.
    (You did say you were looking for >50 V?)

    Cheers
    Roger

  6. #78
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    Re: 1st Build, will this be a decent Design?

    Hi BFP - The Farnell transformer is 122 pound cost (not weight my keyboard doesn't have Pounds) yet switching supplies are cheaper and easier? 2x48V 500W SPS are 39pound each? plug and play? That gives you 2x10A which is overkill! & it can be cranked up to 52V
    Peter

    https://www.omc-stepperonline.com/power-supply/page/2

    Your inductance is 1.8mH so your Vmax is 32*(1.8)^0.5=43V the SPS is adjustable from 42V to 52V perfect....

    2x 48v x8A which is a better match is 23pound each a bargain...

    https://www.omc-stepperonline.com/po...nc-router-kits

  7. #79
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    Re: 1st Build, will this be a decent Design?

    The bit which puzzles me is that 2 of the trannies were <40 quid each, but the slightly higher voltage version with the same powwer rating was 122 quid. Something a shade strange there.

    The advantage of a tranny/diode/cap PS over an SMPS one is that you cannot blow up the tranny by dumping reverse charge from deceleration into it, but you can blow up the SMPS that way. A second advantage is that the RFI from the SMPS can send your driver mad: such drivers are not built to handle that sort of incoming RFI.

    YMMV.

    Cheers
    Roger

  8. #80
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    Re: 1st Build, will this be a decent Design?

    Hi Roger - I have similar ones on three routers (all from Stepperonline) and they work fine. I appreciate the issue of back EMF with SMPS but the inactive motors act as a power sink and if your really concerned you can put caps on the output, plus they are designed and sold for steppers and this issue is incorporated, designed and dealt with in the electronics. Cost of units is proportional to demand. So I expect the higher cost units have less demand. I notice with Stepperonline various things come and go. I expect cost and stock holding are very sensitive to demand. Cheers Peter

    I had to look up YMMV

  9. #81

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    Re: 1st Build, will this be a decent Design?

    Quote Originally Posted by BigFellaPhil View Post
    So I've found this and from what people have said I think it will be suitable, does anyone have any thoughts before a go ahead and buy it... - https://uk.farnell.com/multicomp/vtx...P_LastViewed_1
    Here are some ready to go they have Voltage and Amperage range, PS-10N50 - 1000W 50V Power Supply - AnTek Products Corp
    Mactec54

  10. #82

    Re: 1st Build, will this be a decent Design?

    Hi Peteng - Yeah I was originally going for the Switching Type PS, however after reading a bit more into it and advice/info on here I decided to go down the Toroidal PS route.

    Rcaffin - I kinda thought the 40V would increase slightly when it goes through the Bridge Rectifier (unless I miss understood this?) I thought the 40v would increase to 56v???

    Macec54 - Yeah that PS is what started this thread off, someone else already posted that and I was all set to buy it, then realised they wanted another £100 to deliver to the UK. So now I'm trying to source the parts to make a Toroidal PS myself but finding it difficult to get a Toroidal Transformer here in the UK that matches the specs in your link above!

  11. #83
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    Re: 1st Build, will this be a decent Design?

    You are in the UK, right?
    Try https://uk.rs-online.com/web/p/toroi...rmers/1176080/
    Then wander through their range.

    I have very serious doubts about putting a cap on the output of an SMPS. With some units that can destabilise the whole thing! It may stop working. But you CAN put a double-winding E-core filter to block the spikes. I do this myself on my spindle drive, and it works just fine.

    Cheers
    Roger

  12. #84

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    Re: 1st Build, will this be a decent Design?

    Quote Originally Posted by RCaffin View Post
    You are in the UK, right?
    Try https://uk.rs-online.com/web/p/toroi...rmers/1176080/
    Then wander through their range.

    I have very serious doubts about putting a cap on the output of an SMPS. With some units that can destabilise the whole thing! It may stop working. But you CAN put a double-winding E-core filter to block the spikes. I do this myself on my spindle drive, and it works just fine.

    Cheers
    Roger
    Yes you can use Cap on the output from SMPS, have been doing it for years, one of the Breakout Boards Dmm manufacture has 2 Caps to filter the power from 48V /60v SMPS up to 20A
    Mactec54

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