Power Supply Suggestions please..

[wilfy]

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?

[Jonathan]

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.

[Ricardoco]

Ok I think this is the kiddy....

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

But will it fit the bill????



Rick

[Jonathan]

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

[Ricardoco]

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

[Jonathan]

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.

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.

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...

[Ricardoco]

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

[Ricardoco]

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

[Ricardoco]

Ok, Ive recieved My toroidal which is 4x24 1200VA so using a series arrangement i will have the 50-80vac I require for the Drivers/steppers i will also have 1 or 2 free windings at approx 24vac which is what the contactors require, I will be using an ATX power supply for the smaller relays and the indicator 3v LED's and 5v for the bob as i have one and its easy, im still waiting for the Enclosure which should be here in the week sometime, and the caps im sure i have beneath a few cob webs somewhere.



Looks Like she will be getting that bigger coffee table she has been asking for. cos there wont be room on this one for the rest of the stuff by the end of the week...

Rick

[Ricardoco]

Ok just got the multi meter on the Transformer so i know where im going, atnd im getting 26.76vac using a single winding and 53.6vac using two windings and 80.1vac using three, so if i use the calculations provided by Jonathan of X*1.41 -1.1 to show the rectified Voltage
I get:
36.55Vdc
74.48Vdc
111.84Vdc
Respectively
I will be Using the forth winding else where..

So there is a start

Rick