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  1. #91
    Yes, you don't have to add together the peak demand to give a rating if you are using a linear PSU. For one thing, as you say, the chance that all four motors will be running at full power at the same time is tiny. The second is that the load via the drivers is more like a series of short pulses than a continuous current and the smoothing capacitors can provide this pulse load very easily, and the rest of the PSU components just see the average load. In practice, a rough rule of thumb is to calculate maximum load, and use a PSU rated at about 30% less. The final point is that because of the way the drivers work, you do not actually need a very smooth well-regulated power supply (within reason). My 68V PSU has a measured 10V or so ripple under load. This does not cause any problems at all.

    These points are also why a cheap switch-mode PSU is less suitable. It does not cope with peak loads very well, so it has to be over-specified to cope with the maximum peak load, not an average load.

    I use a 650 VA toroidal which replaced a 500VA transformer which failed. The bigger transformer was only a couple of pounds more, as I remember, but measuring the average power consumption of the machine, I could probably have used something smaller. That's driving 4x3Nm Nema 23 steppers, max current probably about 4A per motor.
    Last edited by Neale; 25-03-2018 at 07:25 AM.

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  3. #92
    Why dual transformers.? Don't see the point just adding expense for no gain. I've built many many PSU's and never had one faulty yet and that's running upto 5 motors.

    I'd also just buy regulated linear 24Vdc supply it's cheaper. Doesn't make any difference just for powering switches or Boards etc and actually better for electronics because don't like flutating power.

    You'd get away with 500Va but 625Va will give little spare current but you might get fuse tripping with inrush in which case just use D rated MCB.
    Voltage then I'd aim to run steppers around 65-70Vdc. So you'll need to check your mains input but roughly 2 x 24Vac for series wired or 2 x 48 for parallel wired.

  4. #93
    Quote Originally Posted by JAZZCNC View Post
    Why dual transformers.? Don't see the point just adding expense for no gain. I've built many many PSU's and never had one faulty yet and that's running upto 5 motors.

    I'd also just buy regulated linear 24Vdc supply it's cheaper. Doesn't make any difference just for powering switches or Boards etc and actually better for electronics because don't like flutating power.

    You'd get away with 500Va but 625Va will give little spare current but you might get fuse tripping with inrush in which case just use D rated MCB.
    Voltage then I'd aim to run steppers around 65-70Vdc. So you'll need to check your mains input but roughly 2 x 24Vac for series wired or 2 x 48 for parallel wired.
    Hi JAZZCNC.

    About the 2 transformers.
    I didnt know a single +/- 600VA would be enough for the 4x 4Amp 4nm steppers.

    Didn't want 1.2 kw setup in a single circuit.
    You mention startup current, i was thinking about short circuit fires :O




    I have a single fuse D type 35amp @ 225 volts in the main panel for the house.

    MCB for the shop power is now16amp B type..

    Maybe dedicated in the future for the machine.

    I have a cable 4x2.5mm2 + PE/screen from the house to the shop at about 25 meters.
    That is 2 spare wires in my book.

    So when i bend the rules a little i can run the machine related stuf from a single mcb 16amps, and the lights and other stuff from some other mcb and combine PE.

    Maybe i need to install some kinda peak shaving setup to stop the domestic equipment like water cookers an washing machines and dryers from running at the same time...

    I already have a Wago 24v DC 2Amp PSU.
    UB1 says 3amps .. i know maybe later ill check if it comes close to 2 amps and upgrade

    Need to do some dumpster diving for relais
    and stuff.

    I did some checking on voltage drop for thecy cable and it looks like 4amps @ 10meters 0.75mm2 is <2 volts.

    So... one might think 4x0.75mm2 + screen is about right for everything.
    Also the spindle should not top 4.5 amps per wire? Quick rule says 3fase 2amps per kw.. so about 4.5 amps at full load 2.2kw.

    http://www.calculator.net/voltage-dr...es=4&x=89&y=22

    Or should i beef up the spindle a little.


    Now for the DIY PSU.


    bom list


    http://nl.farnell.com/multicomp/mclp...nap/dp/1903137

    20.000 uF enough?

    What about 2000hr@85

    is that a good enough rating?



    http://nl.farnell.com/hammond/1182t2...5va/dp/2759999

    dual 24v 625VA



    http://nl.farnell.com/lcr-components...0mm/dp/3885320

    clips.

    http://nl.farnell.com/pro-power/hs40...-2m/dp/1256846

    shrink wrap



    Any critics are welcome


    Grtz Bert.










    Verstuurd vanaf mijn SM-A320FL met Tapatalk

  5. #94
    Quote Originally Posted by driftspin View Post
    Hi JAZZCNC.

    About the 2 transformers.
    I didnt know a single +/- 600VA would be enough for the 4x 4Amp 4nm steppers.

    Didn't want 1.2 kw setup in a single circuit.
    You mention startup current, i was thinking about short circuit fires :O




    I have a single fuse D type 35amp @ 225 volts in the main panel for the house.

    MCB for the shop power is now16amp B type..

    Maybe dedicated in the future for the machine.

    I have a cable 4x2.5mm2 + PE/screen from the house to the shop at about 25 meters.
    That is 2 spare wires in my book.

    So when i bend the rules a little i can run the machine related stuf from a single mcb 16amps, and the lights and other stuff from some other mcb and combine PE.

    Maybe i need to install some kinda peak shaving setup to stop the domestic equipment like water cookers an washing machines and dryers from running at the same time...

    I already have a Wago 24v DC 2Amp PSU.
    UB1 says 3amps .. i know maybe later ill check if it comes close to 2 amps and upgrade

    Need to do some dumpster diving for relais
    and stuff.

    I did some checking on voltage drop for thecy cable and it looks like 4amps @ 10meters 0.75mm2 is <2 volts.

    So... one might think 4x0.75mm2 + screen is about right for everything.
    Also the spindle should not top 4.5 amps per wire? Quick rule says 3fase 2amps per kw.. so about 4.5 amps at full load 2.2kw.

    http://www.calculator.net/voltage-dr...es=4&x=89&y=22

    Or should i beef up the spindle a little.


    Now for the DIY PSU.


    bom list


    http://nl.farnell.com/multicomp/mclp...nap/dp/1903137

    20.000 uF enough?

    What about 2000hr@85

    is that a good enough rating?



    http://nl.farnell.com/hammond/1182t2...5va/dp/2759999

    dual 24v 625VA



    http://nl.farnell.com/lcr-components...0mm/dp/3885320

    clips.

    http://nl.farnell.com/pro-power/hs40...-2m/dp/1256846

    shrink wrap



    Any critics are welcome


    Grtz Bert.










    Verstuurd vanaf mijn SM-A320FL met Tapatalk
    just realise... spindle will do 8 or 9 amps not 4.5...

    Verstuurd vanaf mijn SM-A320FL met Tapatalk

  6. #95
    OK
    1No. https://www.rapidonline.com/vigortro...-x-25v-88-0033
    some people use 24-24v secondary depends how high you mains voltage is. I don't know what your supply is? for the primary

    3 No. https://www.rapidonline.com/jianghai...-4khrs-59-6175

    3 No. https://www.rapidonline.com/lcr-ep08...-clamp-11-3004

    1 No. https://www.rapidonline.com/dc-compo...a-600v-47-1012

    With you having about 225V mains and over a 25 MTr run you could go with 25 - 25 secondary
    625 Va will be more than fine I use 500 Va with 4 3.1Nm 23's with no problems
    20000uf is over kill.

    cy 4 core either .75 or 1mm for the spindle
    Last edited by Clive S; 26-03-2018 at 05:03 PM.
    ..Clive
    The more you know, The better you know, How little you know

  7. #96
    Quote Originally Posted by driftspin View Post
    Hi JAZZCNC.

    About the 2 transformers.
    I didnt know a single +/- 600VA would be enough for the 4x 4Amp 4nm steppers.

    Didn't want 1.2 kw setup in a single circuit.
    You mention startup current, i was thinking about short circuit fires :O
    Yes will handle it easily and your not pulling 16A because of the way drives and PSU work together. You'll be lucky if ever pull more than 6A for any period of time.
    I've probably built in excess of 100 Psu's and most have run 4 x 4A motors




    Quote Originally Posted by driftspin View Post
    I have a single fuse D type 35amp @ 225 volts in the main panel for the house.

    MCB for the shop power is now16amp B type..

    Maybe dedicated in the future for the machine.

    I have a cable 4x2.5mm2 + PE/screen from the house to the shop at about 25 meters.
    That is 2 spare wires in my book.

    So when i bend the rules a little i can run the machine related stuf from a single mcb 16amps, and the lights and other stuff from some other mcb and combine PE.

    Maybe i need to install some kinda peak shaving setup to stop the domestic equipment like water cookers an washing machines and dryers from running at the same time...
    16a supply is more than enough to run machine and anything attached to ie: Vac,Air etc. Again I've built lots of machines which run from a 13a supply often installed in garages or sheds working along side other appliances like Clothes Driers, Washing machines etc and never have any issues.

    Quote Originally Posted by driftspin View Post
    I already have a Wago 24v DC 2Amp PSU.
    UB1 says 3amps .. i know maybe later ill check if it comes close to 2 amps and upgrade
    No the UB1 only requires 0.5A to work, they only recommend 3A to cover all bases so 2A will be more than enough if only powering a few Prox switches etc.

    Need to do some dumpster diving for relais
    and stuff.

    I did some checking on voltage drop for thecy cable and it looks like 4amps @ 10meters 0.75mm2 is <2 volts.

    Quote Originally Posted by driftspin View Post
    So... one might think 4x0.75mm2 + screen is about right for everything.

    Or should i beef up the spindle a little.
    0.75mm2 is fine for motors but for the spindle you'll want minimum of 1mm2.


    Quote Originally Posted by driftspin View Post
    Now for the DIY PSU.


    bom list

    20.000 uF enough?

    What about 2000hr@85

    is that a good enough rating?
    No need to go so high but won't hurt. I usually use 3 x 4700uF

  8. The Following User Says Thank You to JAZZCNC For This Useful Post:


  9. #97
    Thanks JAZZCNC,


    So a lot is on track..

    Can make my bomlist for farnell final than.


    Is there an eu reseller for ub 1?

    Vat/import tax is adding up...

    Grtz Bert


    Verstuurd vanaf mijn SM-A320FL met Tapatalk

  10. #98
    Bert Did you check out the rapidonline list I sent you for the power supply. post #95
    ..Clive
    The more you know, The better you know, How little you know

  11. The Following User Says Thank You to Clive S For This Useful Post:


  12. #99
    Quote Originally Posted by Clive S View Post
    Bert Did you check out the rapidonline list I sent you for the power supply. post #95
    Hi Clive S,
    Uh farnell vs Rapid online.... that was a quick 50% price drop...
    Thanks, you just earned some beers :-)


    Just checked the mains voltage
    Now it is not ~225volts


    It is 235.4 volts on fluke 87 V.
    Oopsie +10 volts, so 24 or 25 volt secondary still?



    Theory : uh was it like ....
    (25+25)*sqrt 2 / 230v*235v?? = 72,2 volts
    (24+24)*sqrt 2 / 230v*235v?? = 69.4 volts
    Goal : 68volts DC

    Well, rectifier steals maybe 1 volt (Vf =1.1 volt) ?

    Can you please confirm? 24+24 is harder to find.



    Post #95 The links are shorted and messed up somehow,
    hard to handle on smart phone icw google, so on a pc now:

    I had google find me the bom list you suggest.

    -DC Components KBPC5006 Bridge Rectifier 50A 600V.

    OK 50Amps@600volts :-) Nice

    1*
    -Vigortronix VTX-146-500-225 500VA Toroidal Transformer 2x115V Primary 2 x 25V
    OK, uh dual primairy? 2 series 115volts=230 volts?

    Do i want single 230v or dual 115v primairy, and why is that?

    3*
    - LCR EP0882-P 35mm Nylon Capacitor Mounting Clamp
    OK


    3*
    - Jianghai ECS2ABZ472MT6P23550 4700uF 100V Snap-in Alum. Elect. Cap. 85° 4khrs
    OK




    Thanks again for this Clive S.


    Grtz Bert.
    Last edited by driftspin; 28-03-2018 at 06:31 AM.

  13. #100
    Hello again!

    Doesnt matter if you have dual 115 primaries or a single 230v. You can connect 2x115 in series to get 1x230 :)

    Same with the secondaries.. you can look for 2x24v or 1x48 or 2x48v .. same thing for your application!

    You might have an easier time finding the right stuff from rs online, just a tip

    For example : https://uk.rs-online.com/mobile/p/to...rmers/1176071/

    Skickat från min SM-G955F via Tapatalk
    Last edited by Nr1madman; 28-03-2018 at 04:15 AM.

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