Power Supply/Motor/Driver questions

[BrassBuilder]

I bought a couple of Pacific Scientific PowerPac motors on ebay and in my haste, I did not see that they were two different DC voltages and I am not sure of a power supply requirement. Here is the info off the labels:

1st motor: (N33HCHJ-LNK-NS-00)
ls(dc) 5A
Vs(dc) 65V
Po: 185 W
1500 RPM

2nd Motor: (N32HCHK-LNK-NS-00)
ls(dc) 6.1A
Vs(dc) 35V
Po: 113 W
1500 RPM

I was going to run two Compumotor OEM750 drives on these.

I'm attempting to CNC my 12" Clausing lathe.

Does anyone have a recommendation for a power supply? Will I need to run two different power supplies to make this work?

Thanks
Mike

[Al_The_Man]

That is a little of a large spread, you could use a 45~50vdc for both, you will not get max rpm from the 65v one.
http://electronicdesign.com/content....&catpath=power
Al.

[BrassBuilder]

Al,
Thanks for the response. I took a look at the article, but that is going to take me awhile to decipher...

Could you point me to which power supply you would recommend? I was looking at Kelinginc.com site and there are a few to choose from. Won't a 45-50V power supply be too big for the motor rated at 35V though?

I don't think meeting the 1500 max RPM is going to be a big deal. The conversion is for my hobby and I am not really big in "rapids" anyway.

I was going to use the 65V motor as the Z axis and the 35V motor as the X. (Z being the axis parallel to the lathe bed.)

Thanks for the help.

Mike

[ger21]

I believe those voltage ratings are maximum voltage. I'd try running them both at 30V.

The N33 is 4.15V, the N32 is 2.75V.

You can find a data sheet here. http://www.xylotex.com/PacSciDS.pdf

[Al_The_Man]

If you read the article it covers voltage range for P.S., as they mention, there is no direct wiring from P.S. to motor, there is a drive in between, the motor per-se, can take a higher voltage as long as it is not at a constant rate, otherwise it would overspeed, the control comes from the drive.
I personally like linear supplies as they are more rugged than switching supplies, there is a guy on ebay makes the toroids and put together the whole supply if needed.
Ebay name Johnango, he also has a web site. Antek.com.
I had assumed these were DC brushed, if stepper, then disregard the suggestion for the 40~50v.
Al.

[BrassBuilder]

Originally Posted by ger21 I believe those voltage ratings are maximum voltage. I'd try running them both at 30V. The N33 is 4.15V, the N32 is 2.75V. You can find a data sheet here. http://www.xylotex.com/PacSciDS.pdf

Gerry,
What are the significance of the 4.15V and 2.75V numbers? I looked at the link and I cannot find anything that mentions those voltages. I was looking on pages 10-37 which covers the PowerPac motors.
Thanks
Mike

[BrassBuilder]

Originally Posted by Al_The_Man If you read the article it covers voltage range for P.S., as they mention, there is no direct wiring from P.S. to motor, there is a drive in between, the motor per-se, can take a higher voltage as long as it is not at a constant rate, otherwise it would overspeed, the control comes from the drive. I personally like linear supplies as they are more rugged than switching supplies, there is a guy on ebay makes the toroids and put together the whole supply if needed. Ebay name Johnango, he also has a web site. Antek.com. I had assumed these were DC brushed, if stepper, then disregard the suggestion for the 40~50v. Al.

Yah...I'm reading. It is just taking me a while to digest it all. I know about the drivers between the motor and power supply. I bought 3 Compumotor OEM750 drives to run this.

I think I am following along. This is not as huge an issue as I first thought when I saw the voltage spread on the two motors.

Oh...and before I forget Al...thanks for all the help on my motor conversion at this thread:

http://www.cnczone.com/forums/showthread.php?t=90889

I got the motor on and used a KB 225R controller and hooked it up with a 220 line. Wow...that made a huge difference. It probably helped that I got rid of one belt and a countershaft assembly during the conversion. I was holding off posting an update until I get the motor/belt cover made and I still need to play around with the pots a little. The motor has a slight hesitation before it speeds up to the RPM setting.

Mike

[ger21]

Those are the rated voltages. Voltage = amps x ohms.

The data sheet shows torque curves with up to 75V, so you may be able to run them at higher voltages.

[lumberjack_jeff]

I used the Mariss formula for determining voltage.

32*sqrt(i)

http://www.mechmate.com/forums/showt...49&postcount=1

Without knowing motor inductance, I don't think we know what the appropriate voltage is.

[BrassBuilder]

Originally Posted by lumberjack_jeff I used the Mariss formula for determining voltage. 32*sqrt(i) http://www.mechmate.com/forums/showt...49&postcount=1 Without knowing motor inductance, I don't think we know what the appropriate voltage is.

Hmmmm.....OK....I should have clarified....I AM electrically challenged. I usually can get this figured out though....

I looked up the mH value on my motors. On the N33 motor, it is 9. The square root of 9 is 3. (That was simple!). So....32x3=96V.

On the N32 motor, the mH value is 5.1. The square root of that is....2.26 (rounded off). 32x2.26=72V (rounded).

What did this just tell me?

Mike

[lumberjack_jeff]

Be aware that the inductance is different depending on which way you wire them.

Assuming this inductance is appropriate one for your intended wiring setup, this indicates that you can use a voltage up to 72vdc without the smaller motor getting too hot.

[BrassBuilder]

Alrighty....I am starting to understand this. I went and looked at my motors and power supply on my mill and got this rated voltage and max voltage thing figured out. Interestingly, the rated voltage on the Pacific Scientific motors are close to the Keling NEMA 23 motors that I am using. The Keling are 4.17V, while I have 4.15V and 2.75. I think I am running a 36V power supply on the motors on the X2 mill.

The rated amps for my motors are 6.1 and 5. I was reading somewhere on cnczone that I need the power supply rated at 67% of the full added amps of the motors (11.1 amps). 67% of 11.1 would be around 7.5 amps.

Al...I emailed that guy on ebay about a power supply. I'm just waiting for a response.

I'm thinking if I got around a 30-36V power supply at around 10 amps, I should be good....I think someone suggested a 30V already in fact...

I think I got this....

(right?)

Mike