Automation Direct power supply . . . or a Switch Mode MeanWell

bfauska · #1 Fri 31 July 2009, 16:06

I've ordered my motors and drives and I'm trying to wade through the information about the power supplies. I think I'm making the power supply information more complex than it needs to be, so I've hunted down a PS I think will work but thought I'd check with some folks here before I order it.

I will be running 4 steppers: OM PK296A2A-SG7.2
With the G540
I found this Power supply at Automation Direct it is dual output with 48 VDC @ 10A (at full load) unregulated and 5 VDC at 0.5A regulated.
My plan is to run unipolar.

Should this work? I don't really have time to source and assemble the parts of a supply from scratch so I'm looking for a turnkey solution and it seems like the only one mentioned on this forum is from a slow supplier.

Any help is greatly appreciated.

bfauska · #2 Fri 31 July 2009, 16:35

OK, further reading has me worried about the voltage. Gerald said Here, that those motors need 35-40v and 8A, so maybe the power supply I found at AD is too high of a voltage.

Is there anything specifically "Stepper Motor" about these power supplies? Can I just find a power supply that delivers 35vdc that's rated for 8A and it will work? How about this one from Mouser.

Gerald D · #3 Fri 31 July 2009, 21:32

Brian, seeing that you are in a big hurry, I would go for the MeanWell supply, but would add an external capacitor, something like this.

(ShopBot have used those MeanWell supplies for a long time.)

domino11 · #4 Fri 31 July 2009, 21:42

Gerald,
I thought you didnt like the switchers? Just wondering.

Gerald D · #5 Fri 31 July 2009, 21:53

Switchers are unnecessarily complicated (expensive), non-repairable, need to be kept clean (their cooling is finicky) and incomplete (need another capacitor) . . . . . but Brian is in a big hurry and it will be a solution for him.

bfauska · #6 Fri 31 July 2009, 23:49

Thanks for the quick reply. I am in a hurry but it's a project at work so I'm working 32hours a week on it and I just need it cutting quickly, I can do some finishing work after the fact. Do you think it's worth doing a custom built unit instead, part of the concern is that I need to save about $35 dollars for every hour I put into a DIY solution for it to really be worth it (of course savings on replacing parts down the road should be taken into consideration too) so if the custom unit is a reasonable savings and will outlast the off-the-shelf unit I wouldn't mind doing it. Whatever the solution I think I need to know what I'm ordering before lunch on Monday so I can keep moving so I may just use the switcher and cap, but I'm definitely open to suggestions.

Edit:
I notice that the capacitor you linked to isn't stocked from mouser, is the ESR a very important factor this capacitor is identical except for the dimensions and the ESR are identical to the one you suggested and it's in stock.

domino11 · #7 Sat 01 August 2009, 00:14

Brian,
The lower the ESR the better. In either case for your application 24mOhms vs 29 mOhms is negligible.

domino11 · #8 Sat 01 August 2009, 00:37

A good place for transformers is Parts Express.
examples that would give you about 36V after rectification and filtering are:
http://www.parts-express.com/pe/show...number=122-655

http://www.parts-express.com/pe/show...number=122-640

and a bridge rectifier

http://www.parts-express.com/pe/show...number=050-060

and then the capacitor you mentioned from Mouser would make up your own unregulated linear supply.
I might be tempted to use a slightly large capacitor like this one
http://www.mouser.com/Search/Product...jltYFsVafm0%3d

see also this thread. on capacitors.
http://www.mechmate.com/forums/showthread.php?t=53

Gerald D · #9 Sat 01 August 2009, 00:57

I just took a quick stab at a Mouser capacitor, to complement the capacitance already in the switching supply, which theoretically already has very low ripple. I go 100% with Heath's advice - sue him because he is nearer to you.

Seriously though, knocking together the power supply is simple and a small part of the overall MM build.

Although I have the greatest respect for MeanWell's products (solid engineering and build quality), we have clogged one with sawdust and burnt it beyond repair. The DIY built supplies, based only on a simple toroid transformer, rectifier. capacitor/s just keep going on and on forever.

bfauska · #10 Sat 01 August 2009, 15:06

I am a huge fan of "learning by forum" and I've done some hobby and work projects with quick supportive forums and some with rude holier-than-thou posters, this is definitely a forum for my short list of quick, supportive, knowledgeable, and friendly places to learn online. Thanks again for the quick replies.

It sounds like it's probably a financial wash between the two options since my time actually costs money (on personal projects I value my time at about $0.00 an hour, but for work they do pay me) so I'll have to weigh the options and order on Monday. If all the parts end up in the control box I don't picture dust being much of an issue, I'll either do sealed or filtered fan, but I think since I'm a sucker for building stuff I may just go with the tried and true DIY supply. Of course I'd never imply that you said it was safe or easy

and it's certainly not my first foray into mains level wiring.

domino11 · #11 Sat 01 August 2009, 16:52

Brian,
Actually, if you count the number of connections (of wire) to hook up the switching power supply and capacitor vs the diy transformer/rectifier/capacitor, you will find that it is very close. The time wise will be very similar. (hour wise) if you need an excuse for the boss.

Crimp connectors (1/4" spade type) make this really easy. The bridge rectifer comes with the spade terminals already for the mating half.

If you have other sources for transformers let us know and we can recommend one from your supplier of choice.

bfauska · #12 Sat 01 August 2009, 18:37

Heath,
Conveniently my boss is logical enough that I could explain that the slightly slower process gives us a more reliable product for about the same cost and he'd be fine.

I'm perfectly content with PE, I've used them plenty for personal projects and I think we've even ordered from them at work before (probably because I use them outside of work.)

domino11 · #13 Sat 01 August 2009, 20:27

I have used the toroids from PE myself and they have been fine. The only problem with PE is they dont stock any good higher voltage capacitors.

Richards · #14 Mon 03 August 2009, 08:42

The problem with switching style power supplies is that they normally have sophisticated feed-back systems to keep the voltage tightly regulated. Stepper motors run perfectly fine with "loose" regulation or no regulation at all.

Many switching supplies have a voltage adjustment pot so that you can vary the output voltage. Sometimes those pots let you dial in exactly the voltage that you want.

As Gerald suggested, a large capacitor on the output is essential. A stepper motor requires current in pulses, so a regular switching power supply would have a hard time keeping things regulated. The capacitor creates a current reservoir that helps the switcher.

My advice would be to use a switcher only if you have one on hand; otherwise, buy a transformer (toroidal is best), a bridge rectifier and a capacitor or order a complete unit from AnTeK.

Gerald D · #15 Tue 11 August 2009, 11:16

Brian decided the unregulated toroid route, story continues here:
Building own 35V supply, based on Parts Express toroid transformer