servo power supply

[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]

Originally Posted by krymis 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.