[krymis]

need some help making a servo power supply. I have three servo motors already. I have the print out of each motor. One is different than the other 2 in terms of size and power. How do I figure out what i need? I know I want to have 65V at 20A unregulated power supply. I need to know what toroid transformer to get and from where. I know John at Antek said his 48V @1000VA would do it, but i thought it would have to be 65V? Also I have my cap picked out. It is a Mallory CGS373U075X5L. Here is the links to each of the parts so far.... transformer
http://www.toroid-transformer.com/AN-10248.pdf , and the cap
http://www.newark.com/jsp/displayPro...=CGS373U075X5L

I need to know what rectifiers to get and where also. And last what filter cap.

motor 1 and 2: Terminal Resistance=3.64 ohms, Inductance=5.58mH

motor 3: Resistance of armature at 25 deg. C=0.67ohms, Inductance of armature at 1000hz=0.74mH, Terminal Voltage=85V, Amps at Peak torque=20
I can try to give you more info if needed on the motors

[krymis]

I have read through both the gecko and campbell power supply pages. Is there any difference between the servo power supply and the stepper power supply.

[Al_The_Man]

The 48v toroid will give you about 67vdc, 48x1.414.
I usually size current for around 60% of total continuous motor stall torque current.
The bridge rectifier is common for any supplier, 35amp 100vpiv minimum.
Al.

[krymis]

why is that i have a power supply right now that has 2 bridge rectifiers? Is that a common set up?

[Al_The_Man]

why is that i have a power supply right now that has 2 bridge rectifiers? Is that a common set up?

There are several reasons, two separate windings or supplies, either different voltages or different polarity WRT common.
Al.

[krymis]

So basically I would only need one rectifier? I would just need to get the one you stated earlier?

[Al_The_Man]

Yes.One bridge rectifier, for single supply.
Al.

[krymis]

I was looking at www.digi-key.com for the recifier. What one do I need or should I want? I know I want one with the spade terminals for ease of connecting.

[Al_The_Man]

GBPC3501/1 around $6.00 . don't forget to mount it on heat sink preferably aluminum plate.
Al.

[krymis]

Al,

How did you size that? Do you just find one that has more Amp and Volt listed than what you will need once rectified?

[Al_The_Man]

There is virtually no saving in cost by sizing to exact specifications, Unless size is an issue, I usually allow a generous tolerance for these kind of components.
Al.

[krymis]

Awesom, thank you for helping me through this aspect. The next hurdle is the bleeder resistor. I have read there is no need for one unless you just have the power supply and no geckos wired. Is this true. I know my IH mill has an item on the top of the capacitor. I would assume that is a bleeder. If it is, is there any reason the manufacturer would have that on there. Also this page has pictures of my IH power supply with the 2 rectifiers, and the item on the cap http://www.cnczone.com/forums/showthread.php?t=23145
It also shows the fuse that the power line goes to. Is there any reason for that also? Shoud I look at putting that fuse in the P.S. even if I am planning on using an AGC 4 fuse block to protect the geckos?

The lines for the rectifiers got from one leg on the power supply split into 2 (the blue line)and then going to ~ on each of the rectifiers. The other line from the p.s. (white) is split into 2 lines and goes to the other ~ line on the rectifiers. THen a red line goes from the + on one of the rectifiers to the plus on the cap and then over to the fuse. On that rectifier the - is empty. The - on the other rectifier goes over to the - on the cap. Is there any way you can tell me what is going on there.

[Al_The_Man]

For most of the systems I have installed, I have never used a bleed resistor, In my opinion, I you want to use one, do not use too low a resistance/high wattage value, as what you are doing is draining off the peak charge that you have gone to the trouble of producing with the electrolytic caps.
If the voltage level is such that is is not in the life threating range, I would not bother.
Al.

[krymis]

Al,
I add more as you were typing. Can you help on the other stuff too?

[krymis]

edit the white and blue lines go to opposite tabs on opposing rectifiers ie if the white line goes to the left~ line on one rectifier it then goes to the right~ on the other rectifier.

[Al_The_Man]

The lines for the rectifiers got from one leg on the power supply split into 2 (the blue line)and then going to ~ on each of the rectifiers. The other line from the p.s. (white) is split into 2 lines and goes to the other ~ line on the rectifiers. THen a red line goes from the + on one of the rectifiers to the plus on the cap and then over to the fuse. On that rectifier the - is empty. The - on the other rectifier goes over to the - on the cap. Is there any way you can tell me what is going on there.

I could not really see the actual link you referred to but give me the post #, If you intend fusing the DC side, make sure it is between the bridge and the caps.
I normally fuse the AC into the bridge, which is a better scenario.
Al.

[krymis]

Al,

It is post #12. It has pictures of all the sides of the power supply. that post shows all the parts I wanted to know about. Somethings on this power supply just don't make scense to me. They could cut a few bucks here and there and make a product a little cheaper and easier to use.

Is there any size bleeder resistor I can put on and leave on? If I did it what size would I need? I am not worried about waiting 5-10 minutes for discharge.