# Thread: Which Power Supply ?

1. ## Which Power Supply ?

If I were to buy "3" of the following motors(kelinginc), which power supply would I need? I tried to follow the formulas that another member posted but got lost along the way. Not a failure at math, just not familiar with electrical terms and meanings.

NEMA 23 Stepper Motor: KL23H276-30-4A (1/4" Single Shaft with flat) 282 oz-in Specification Price: \$39
282 oz In. Hybrid Motor
1.8° /200 Steps Per Rev.
3 Amps Current Per Phase ( Bipolar Parallel)
4-wire Bi-polar, NEMA 23 Frame

On a side note, can motors be considered overkill or just underutilised? Instead of mixing motors, just all the same, whether the loads are the same or lesser. Any help would be greatly appreciated.

2. When I bought my PSU I bought one that had the higher amperage above my steppers drivers,the steppers and drivers then can only draw the amount of current thats needed from the PSU,best to be higher than less current.

Make sure the voltage is correct as well.

3. I have no problem getting a bigger power supply. I just don't understand how to figure out which one is needed. I could just as easily pick the whole kit, but I would like to learn the electrical aspects of it.

4. 15amps or above will do.

I personally don't care about working it out as my drivers are rated/set at 3.9 amps a piece and 3x4 = 12 amps so I got a 15amp supply because as I said the drivers will only draw the current they need from the supply.

5. Here is an easy guide to sizing a Stepper power supply:

Calculate voltage and VA of power supply

If this is your first time, you will be surprised at how much higher the voltage is than you would guess.

6. Originally Posted by vid1900
Here is an easy guide to sizing a Stepper power supply:

Calculate voltage and VA of power supply

If this is your first time, you will be surprised at how much higher the voltage is than you would guess.

Thank you so much!

7. What drives are you using? They can effect your voltage decision.

8. I don't know yet. I have been holding off because I didn't wanna get something that would make my setup a hassle. So I am open to whatever ideas you have. I haven't bought any electronics for the main fact that I don't want to overspend on a kit that does more than I need. I am sure I keep hearing that 425oz motors are used in tables 4' x 8'? So I was thinking my table is more or so a little less than half that. Gantry weighs less that 10lbs. So I am thinking 282oz Motor. I don't know how to match up drivers with motors, and then with the power supply. The equations lose me, or I am missing something.

So using that motor, what do I need to look for in a driver? For arguments sake, you can suggest one and it would be helpful to explain how to get to deciding a power supply. #ifeelsoneedy

9. the main fact that I don't want to overspend on a kit that does more than I need.
A power supply is not an overspend,in fact the more amperage you can afford on the supply the better as future improvments might ensue? supposing you wan't to add a 4th axis? now and you buy a 12amp supply now then you will have to buy another supply when 4th axis is added as the 12amp might not be up to it,so its best to get the max PSU you can afford.

This then leaves you the drivers and motors to worry about,its clear cut.

I can tell though that power supplys can be connected in series or parrallel to up the Voltage or Amperage,but you need to get advice on this before doing the link up.

10. Btw I wasn't referring to a power supply kit, I meant an entire setup kit. I want to choose all pieces individually to fit my needs. But duly noted. What I am having an issue understanding is v/amps. If the power supply has 48v and 10 amp, My motor for example uses 42v 2 amps. If I have 3 motors, does that mean I need a total of 126v and 6 amps not including drivers?

11. My motor for example uses 42v 2 amps. If I have 3 motors, does that mean I need a total of 126v and 6 amps not including drivers?
No,42v is constant for 3 drivers,the motors get driven by the drivers and the amps is vital to the motors.

12. So let me see if I have this right. I need a power supply that provides at least 42v and at least 6 amps just for the motors? If that is so, then I also need a driver that uses 42v +/-? Do I go over or under voltage? For arguments sake, my driver needs 48vdc, what does that mean in reference to v/amps?

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