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.










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