How'd you supply your power supply?

[cnczane]

[Fourth try; 2 lost to the Esc key, 1 to trying to edit in preview. In Unix, the Esc key is vi's way to edit things. In the forum, it's start over, way over.]

Briefly (this time ), how'd you get your power supply? I'm hoping to see short posts like:
"vV@aA for $d from ."
"built vV@aA for $d from schematic from "
"cannibalized vV@aA from for $d from "
"grandmother gave me hers, vV@aA."

fwiw, I:
"need 14-30V@20A" for three PowerMaxII M21... wired bipolar parallel (lowest current, highest torque), 2.8A/phase x 2 phase/motor x 3 motor = 16.8A.

I hear the higher voltage the better in terms of response, but the bipolar drivers I've seen aren't happy above 30V.

I also hear "don't use switching supplies with steppers," but that may be only for drivers using current chopping.

Appreciate any posts, thanks. (And I ain't previewing neither. Been there, lost that...)

[ullbergm]

These may be too much if you are looking for 30v.. but i bought mine of ebay
http://cgi.ebay.com/ws/eBayISAPI.dll...tem=3059598209

Traco Power TSL480-155PX Industrial Power Supply
Input: 93-264VAC Auto-ranging, 50/60Hz
Output: 48-55VDC Adjustable, 480 Watts, 10A

they are $50.
i'm expecting them to arrive either friday or monday.

[cnczane]

I'd almost despaired of ever seeing another power supply on ebay ever again.

I was searching the internet for "high-amperage" circutis (found a 12V/30A at http://www.mitedu.freeserve.co.uk/Ci...er/1230psu.htm btw) when I found a:

24V/50A on ebay for $80.

(I have to say that $80 looked cheaper and cheaper as frustration at finding a suitable circuit mounted.)

Note to self: Buy controller THEN steppers rather than v.v.

[samualt]

Look for Power Supplies on Ebay that are for telecom equipment. There is lots of surplus out there and many handle pretty big amps. Many are 48 volts (some can be adjusted slightly higher or lower).

It may take awhile to find the price you want. But I found a 60V 30A (1800W) power supply and paid only $49.99 on Ebay.

Just be careful and stay away from anything that says "3 phase". Also, check and make sure it's 115V-in if you don't have the proper 220V outlets (220V come with different plugs for different amps).

Ebay Search Terms:
Power Supply 48
Power Supply amp
Power Supply CRU (charging rectifier unit)
Power Supply Cherokee
Power Supply Lambda
Power Supply Kepco
Power Suplly Siemens

[ger21]

Search Ebay for "24V power supply". There are usually quite a few.

Gerry

[cnczane]

One more thing to watch is that some of the telecom supplies are DC-DC converters. If you get one of those, you'll still need a classic AC-DC power supply to get you from wall to the input DC voltage.

[DaSigntist]

I'm did like ullbergm but I bought 2 from the guy on eBay and will hook them up to achive 48V 20 amps.

I'm running 1100 oz/in servos.

[AussieMatt]

I want to also change from my 4x 48V 7.5A(output) PSUs to one or two larger PSUs (on a project I have yet to finish...)

I have 4x 900W(peak) Servos that this will be suppling power to through DMM-Tech control gear.

I haven’t talked to the Hui at DMM-Tech for a while but will pose the question to him as well, but thought it would be good to put it up here with your post as well.

Note: he was meant to give me three of these PSUs but gave me 4, which still seems underpowered for the system, I don’t want one axis to be underpowered at any one time while waiting for the others to move….

I am a little rusty on this power conversion as haven’t been working with it for a long time (project has been put on hold far too long), and was wondering which side to keep constant in the upgrade, the amps or the volts or does it matter at all?

Cheers

[cnczane]

Originally Posted by AussieMatt I want to also change from my 4x 48V 7.5A(output) PSUs to one or two larger PSUs (on a project I have yet to finish...) I have 4x 900W(peak) Servos that this will be suppling power to through DMM-Tech control gear. I haven’t talked to the Hui at DMM-Tech for a while but will pose the question to him as well, but thought it would be good to put it up here with your post as well. Note: he was meant to give me three of these PSUs but gave me 4, which still seems underpowered for the system, I don’t want one axis to be underpowered at any one time while waiting for the others to move…. I am a little rusty on this power conversion as haven’t been working with it for a long time (project has been put on hold far too long), and was wondering which side to keep constant in the upgrade, the amps or the volts or does it matter at all? Cheers

AM,

I'm surprised--after all these years--to find myself reading posts from my younger self (who I must say, seems much more informed than I...).

Taking my own post as a hint, I guess that I would look up the specs on the servos, find the voltage it's going to run at, see the maximum current it's going to draw at that voltage, multiply by four (4 servos), and find a PSU that outputs that much current at that much voltage.

Power (in watts, W) is just voltage x amperage.

If you have a 48V supply, your 900W servo needs 900W/48V > 18A (peak). However, if you found a 100V supply--AND they were designed to work at that voltage--they'd need only 9A.

Maybe you could put a clamp-ammeter (clammeter?) on one to test it's draw and see that it's suck 7.5A (should blow a breaker if it tries to draw more than rated current from the PS).

Does seem a little underpowered to me, but "Golly, Batman, do we really NEED 4 KiloWATTS for this project?!"

Turning over and going back to sleep for another 8 years...
--
Czzzzzz

[Bubba]

To the OP,
I built mine from old Microwave transformer. See instructions at: CNCzone.com-Machinist Community Forums - Magazine - Home Made Machine How-to's - Build a power supply transformer (by Bubba)

Its been working great for about 10 years now.

[AussieMatt]

[QUOTE=cnczane;983573]

Yeah I initally done the same equation, 900W x 4 Servos, but as its peak power and not continous it is apparently not needed to have sooo much power supplied. As capacitors and such in the controllers will make up for the lack of power (or so I am told), regadless it seemed in logic to be still way to low having only 4x 350W PSUs suppling the power.

Also I found the breakout board is limited to 48Vdc and 30A so in order to get more power the motors I might have to by pass the BOB. As such I am probably going to meet half way with the 900W x4 and the current level and get a 1.5KW supply at first hooked up through the BOB and then later if I feel it needs more get another 1.5KW and bypass the BOB for two Servos power (connecting the Earths together).

Or even possibly starting with 1KW (less then I currently have, but a lot more managable space and cableing wise) and getting a 2KW to bypass the BOB for three motors later.

Although with above I am unsure on two things (waiting on reply from Hui at DMM-Tech), First) If I by pass the BOB can I use one power supply to supply power to multiple other Controllers/Servos or do I need to give each one a seprate power supply?
Second) can I use different sized power supplies for the BOB passthrough one compared to the others? (I am pretty sure this wont be a problem, but ever one has been talking to me in multiple powersupplies for seprate Controllers.... so I thought I better put it out there)

[JohnZ]

I built my PS by purchasing a Toroidal transformer and rectifier module from Antek Inc. For a 30V x 20A power supply, you would need a 20-22volt transformer outputting 600 Watts. This type of transformer is designed to handle overload conditions typically 2x the rated output, and can output 20% higher rated power when run on 60hz instead of the rated 50hz, so a 600 watt transformer when run on 60hz (US) is actually a 720 watt transformer and can handle overloads of 1200 watts (50 hz) or 1440 watts (60 hz). When building a power supply like this, the AC RMS voltage when used with a bridge rectifier and smoothing capacitors will have a DC output voltage about 1.41 times higher than the AC output by the transformer.

I would recommend the following items ...

Antek DC80 - 80vdc 35A bridge rectifier module $25.00
and your choice of the following transformers
Antek 5220 - 500 watt (50 hz) 600 watt (60 hz) 20vac output (~28.2 vdc output) $55.00
Antek 5222 - 22vac output (~31.02 vdc output) $55.00
Antek 8420 - 800 watt (50 hz) 960 watt (60 hz) 20vac outpup (~28.2 vdc output) $84.00

Note: their 600 watt transformers are either 18v or 24v ac output putting you a bit too high or low if you are targeting about 30vdc output.

One possible option is to use these transformers with multiple rectifier modules to create multiple lower wattage outputs. For example, the 800 watt power supply has four AC outputs. You could use these to create four 200 watt power supplies, two 400 watt power supplies, one 600 watt plus one 200 watt power supply etc. What I mean by this is that you could create an output for each servo driver so each driver is on its own rectifier module (and set of capacitors) minimizing the effect of power draw from one motor to the next ... to a point that is anyway.

Putting together one of these is extremely simple. You hook up line voltage to the input wires on the transformer, connect the output from the transformer to the input terminals on the rectifier module, then connect wires from the output terminals on the rectifier module to your servo controllers, and to be on the safe side, connect a wire from the negative output of the rectifier module to ground to eliminate the ground path from going through your servo controllers, and to make everything more stable.

The advantage of this type of power supply vs a switching power supply is that it will not shut down on overload. I had a problem with a switching power supply a while back that I traced down to auxiliary capacitors. Sometimes the switching power supply would shut down a few seconds after startup. It was the charging current going into the capacitors triggering the overload circuit in the power supply. I had to remove input power to the power supply to reset it, but had no guarantee that it would power up again. I replaced this setup with the one described above and couldn't be happier. In my case, I built a 720 watt power supply with both 40v and 80v outputs for a total of $110 including shipping that can handle a 1440 watt overload for 60 seconds.

Take a look at their site. I have no affiliation with them, I am just a happy customer.

Thanks - John Z