Holy cow!

I must me learning something here. That is the type of transformer I have been looking at. I just wasn't sure the 10amp would be enough. Do you think that one transformer would be enough sarge. From what I have gathered through the information posted here, it should be plenty....right?

What do the specifications for your motors say?

I think that by using that 24VAC 10A transformer, you should at least be able to step one motor at a time. What I don't know is the holding current that the other two will require simultaneously.

Remember, the original transformer was rated 5kVA, and this one is rated 240VA. It appears they were running a lot more than just three steppers and three drivers from it.

Since the supply was unregulated, having massive overkill in the supply pretty much guarantees that the output will remain within a fairly narrow range.

I have no way of knowing how much current your steppers actually require, except for in the schematic there were 20A fuses on both sides of the bridge for your three steppers/drivers combination - so that pegs the current limit down.

You might find that a single transformer is sufficient to run one, or maybe even all three steppers.

Since these transformers are pretty cheap, I think I'd get one per stepper/driver combination, and use a bridge rectifier, cap, and bleeder resistor for each.

 

Sarge,

The transformer in the link is AC. Is that right?

 

Sorry, just got your last post. The original transformer ran 9 drivers and motors. I thought I had mentioned that. If if didn't I apologize because it seems a fairly key piece to the puzzle now. The above post might not be clear either. I thought we were shooting for dc? Wait, I guess if we put it throught the rectifier and cap still we will get DC. I think i'm with ya.

 

LOL!

Look at The_RB's post; he was writing his as I was writing mine (ie: cross-post).

So, if there were originally 9 motors/drivers being powered by one 5kVA transformer, that means 555VA per motor/driver combination, or 1.7kVA for three motor/driver combos, with a 20A limit, and the voltage limitation of your stepper driver maximum voltage.

 

alright guys I feel like we are getting somewhere. You keep saying that I need to add extra power for the driver power supply. The drivers have and extra supply of 12vdc. I am assuming this is the driver power supply. If you look at the schematic they are wire number 12p and 12c. Does this seem like it could be the case?

 

Looks like that to me as well.
12P is +12V DC, 12C is the return (ground) for +12V.
There also seems to be input for logic power, 5P on terminal 9.
However, +5 VDC is also shown on terminal 5.
Terminal 2 is confusing, as on the left it's shown as connecting to 5P, in the middle and right it's shown as connecting to 5C - but it's labeled as DIRECTION.
Terminal 6 shows as unconnected. However, one would think that it would go to the 5v return.

You really need the manufacturer's documentation for these driver units in order to properly resolve these questions. Just hooking it up to try it will likely result in lots of smoke.

Converting a used ATX form factor computer power supply might be an option for the +12v and +5v logic supplies. You'll have to refer to the drive documentation to determine what's needed though.

 

Currently I have purchased a standard radioshack AC/DC wall plug power supply to get the 12vdc, but I was hoping that the 5v would come from the parallel port I am hoping to use to control this mess. I am going to use Mach3. If you haven't heard of it, it is a program that basically runs a g-code and sends out output signals from your computers parallel port. (5v signals). Sound like it might work to you??

 

Currently I have purchased a standard radioshack AC/DC wall plug power supply to get the 12vdc

"Wall warts" are not typically regulated.
How much current the drivers require is an unknown. It might be 100mA, it might be several amps per driver. If they're using power MOSFETs to control the steppers, and you're stepping them fast, it could be a pretty good drain.

I was hoping that the 5v would come from the parallel port I am hoping to use to control this mess.

Not a good plan. Parallel ports are for signals, not for power. You will probably wind up smoking your port if you try to power much more than an LED with it.

I strongly suggest to use an aftermarket parallel port card, commonly called a multi I/O card. If you fry the aftermarket card, you can replace it for $10 instead of smoking your computers' motherboard.

I am going to use Mach3. If you haven't heard of it, it is a program that basically runs a g-code and sends out output signals from your computers parallel port. (5v signals). Sound like it might work to you??

The signal part might work OK. I don't have a CNC setup here, so I can't really advise you on that part.

 

Here are some possible transformers from Ebay;

http://cgi.ebay.com/Toroidal-Power-...uit_Breakers_Transformers?hash=item2c5081a89e

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=330385136785&ssPageName=STRK:MEWAX:IT


http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=360217315683&ssPageName=STRK:MEWAX:IT


I haven't kept up with the DIY CNC stuff, but at one time the toroidal transformer was the way most people were going for motor power supplies.

At the amount of Amps you are needing I personally go with 220VAC for the primary supply voltage.

You could use a computer power supply for your 5VDC and12VDC.

Cary

 

I was thinking the 5v was a signal because, on the original schematics, it comes from an I/O card on an industrial computer (not a plc). Looks like I have a lot to learn.

 

I was thinking the 5v was a signal because, on the original schematics, it comes from an I/O card on an industrial computer (not a plc). Looks like I have a lot to learn.

The signals for the drivers are digital- "1"= 5VDC "0"= 0VDC. But the drivers also need a constant 5VDC for the logic circuit. The interface on the driver is opto-coupled, thats why it needs a constant 5VDC, on pin #9 at J/3 as shown on your print. The ground(0V) from that supply goes to pin#6 on J/3.

 

Here is the data on a Pac-Sci 6410 driver;

 

Shortbus,

That makes sense to me

 

Okay, let me run this by everyone. I had a nice converstion with a local electrician. He suggested this:

Get a standard 480/240 to 240-110 transformer (1.5kva). Then hook up the 110vac to the 240v on the primary side. He says it should put out roughly 48vdc once it has been put through the rectifier and the stabilizer. At the 1.5kva that puts me at about 31amps going into the drive. 8amps per motor *3 motors = 24amps. Would it hurt to be a little high? Anyway let me know your guys thought on this. I know those transformers are expensive, but I think I have access to one.

 

Having overcapacity means never having to buy more.

Ahh, wait a minute.
Better post a link to the transformer you're considering, or post the datasheet.

As I said before, the original specification on the schematic was 5kVA/9=555vA per motor/driver combo. With the proposed transformer, you'd be just about on target without a lot of fiddling around.

 

Sare,
remember that powered 9 motors and drives though

 

If you could use the 480VAC in and 120VAC out, powering the 480VAC primary with 120VAC, you'd have 30VAC out of the transformer; after rectification and filtering you'd have about 40.3 VDC with no load.

That's assuming you will lose about 1.5v across the rectifier diodes.

 

You really should consider using 220/240V on the primary of your transformer. The usual highest amperage on a 110/120V circuit is only 20Amps.

When you figure in a router or what ever on your spindle, you will need two separate 110/120V circuits for the machine. Just trying to think ahead for you.

Also have you thought of what soft ware you are going to use to drive your machine?

 

To use 240VAC in, he'd need an 8:1 1.5kVA transformer.
The transformer he's considering could only go 2:1 or 4:1, unless I'm not understanding something correctly.

 

Sarge,

I think shortbus is saying that even if I were to get the 120v to work through the transformer, I wouldn't be able to pull enough current. Were my calculations on the current correct? Getting 31amps out?

Would that work with the transformer??