60-70v unregulated power supply recommendations

[JoeHarris]

I see that Joe used a massive 750VA transformer.

Hi, for the record mine is a 625VA tx.

[johngoodrich]

hi. this is what jazz sent to me for my psu. i'm running 2 4nm nema 23's and a 8nm nema 34 and it runs absolutely fine

You'll need:
Transformer with 2 x 25V secondery coils with 625Va output.
1 x 35A 300V or higher Bridge rectifier
3 x 4700uf 100Vdc capacitors with holders.

This transformer will work.
http://www.airlinktransformers.com/c...nge/CM0625224/

This Bridge rectifier.
http://uk.rs-online.com/web/p/bridge...fiers/6296320/

Capacitors
http://uk.rs-online.com/web/p/alumin...itors/8712748/

Brackets:
http://uk.rs-online.com/web/p/capaci...clips/2035698/

if you search for it there is also a wiring diagram for it on here somewhere. all you need is very basic soldering skills and its easy to do

[john swift]

Hi John

the link to the transformer does not work
a web search for the part number cm0625224 links to

https://airlinktransformers.com/prod...ange-cm0625224

power supply circuit



I notice that data sheet for the transformer does not specify the transformer regulation (change in output from no load to full load)

the 24V output from each secondry is when fully loaded
I expect off load it could be 5 or 6% higher

in my part of the UK, depending on the time of day
the mains supply is 243 to 248 V RMS

when the mains supply is 248V
the DC power supply output can be about 77V DC off load
or 73V DC fully loaded

John

PS
with my mains supply of up to 248V
If I decided to build a power supply
I may opt for CM0625222 with two 22V outputs wired for 44V
to give me 71V DC off load

[Neale]

John - for the reasons you suggest (load regulation/mains variation), I went with a 2x45V transformer with the secondaries wired in parallel. I used a 625VA Vigortronics toroidal from Rapid Online. You could get the other components from Rapid as well and maybe get free postage. I'm using EM806 drives that are good for max of 80V and nothing's gone pop yet!

Judy a thought.

[JoeHarris]

John - for the reasons you suggest (load regulation/mains variation), I went with a 2x45V transformer with the secondaries wired in parallel. I used a 625VA Vigortronics toroidal from Rapid Online. You could get the other components from Rapid as well and maybe get free postage. I'm using EM806 drives that are good for max of 80V and nothing's gone pop yet!

Judy a thought.

2x45v? woocha!!


Sent from my iPhone using Tapatalk

[john swift]

Hi Neale

The other variable is when an axis decelerates and the motors becomes generators returning energy back to the power supply capacitors

the voltage at power supply terminals could be increased beyond the drivers limit
if the decelerating axis returns a lot more energy than other axis use and the power supply capacitors can absorb

John

PS
Hi Joe
the great thing with the 625VA transformers with Bifilar wound 45V secondaries is they can be connected in parallel to give you 45V at 13.88A
you just get the phasing of the winding correct !!!

[Agathon]

Hi Neale

The other variable is when an axis decelerates and the motors becomes generators returning energy back to the power supply capacitors

the voltage at power supply terminals could be increased beyond the drivers limit

John

Plenty to think about here for the electronically semi-literate like myself. I think keeping the voltage around 70v seems sensible. Is there any disadvantage to using a transformer with a pair of 45v secondaries in parallel? Conversely, any advantage to using a 24v in series?

Rapid Electronics seems like a good place to buy. Is there anything I need to look out for when buying capacitors? I believe there are differences in quality from one manufacturer to another - I don't want to spoil the ship for a ha'porth of tar.

[john swift]

Hi Agathon

in power supplies its worth checking the ripple current rating of your capacitors is OK for your circuit
and if available buy 105°C high temperature capacitors that can run hotter than the 85°C standard electrolytic capacitor

John

for ripple current
http://www.skillbank.co.uk/psu/ripple.htm