Power Supply Suggestions please..

[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

[Jonathan]

Yes that's better, still seems OTT though. 4x25v would have been slightly better, but it's not a big deal.

With that transformer you will be able to get multiples of 35V, so 70V for the motors and 35V for other things. What voltage do the other things require?

[Ricardoco]

Yes that's better, still seems OTT though. 4x25v would have been slightly better, but it's not a big deal.

With that transformer you will be able to get multiples of 35V, so 70V for the motors and 35V for other things. What voltage do the other things require?

The other things range from 12v to 32v but the contactors can be what ever i want when i order them.

[Jonathan]

The other things range from 12v to 32v but the contactors can be what ever i want when i order them.

Presumably the contactors are just to switch these other things on and off?
The absolute minimum you can get from the transformer you have bought is by using one 24v winding, which when rectified will give 24*2^0.5-1.1=32.8V which is clearly above 32V so probably not much use. Also the tolerance on the mains voltage (230V +10% - 6%) means that it could be up to 32.8*1.1=36.1V.

How much power do these other things need? Can you provide a list of voltage and current or power that each device uses so we can work out the best transformer? It sounds like you'd be much better off with a separate transformer, perhaps 16V.

[Ricardoco]

Presumably the contactors are just to switch these other things on and off?
The absolute minimum you can get from the transformer you have bought is by using one 24v winding, which when rectified will give 24*2^0.5-1.1=32.8V which is clearly above 32V so probably not much use. Also the tolerance on the mains voltage (230V +10% - 6%) means that it could be up to 32.8*1.1=36.1V.

How much power do these other things need? Can you provide a list of voltage and current or power that each device uses so we can work out the best transformer? It sounds like you'd be much better off with a separate transformer, perhaps 16V.

If i was comming out and used non regulated that would be a problem but i will build a circuit to give me all the voltages i will ever need. Besides which they are on their way to me this moment.

rick