Will these steppers cause any problems

[Mariss Freimanis]

Rift,

First, thank you for buying our drives. Second, don't even think of using a 72VDC power supply with the motor you selected!!!

Your motor specs-out a 1.18 mH winding inductance. The maximum power supply voltage equation is VDC = 32 times square-root mH. That works out to 34.7 VDC (32 * SQRT 1.18 = 34.7).

Your motor temperature will reach 85C or 185F (motor's rated max temperature) with a 35VDC power supply. Your motor will glow red-hot with a 72VDC power supply. Try it at 24VDC and you may find that is plenty and your motor will stay below 70C.

Mariss

[Rift]

Rift,

First, thank you for buying our drives. Second, don't even think of using a 72VDC power supply with the motor you selected!!!

Your motor specs-out a 1.18 mH winding inductance. The maximum power supply voltage equation is VDC = 32 times square-root mH. That works out to 34.7 VDC (32 * SQRT 1.18 = 34.7).

Your motor temperature will reach 85C or 185F (motor's rated max temperature) with a 35VDC power supply. Your motor will glow red-hot with a 72VDC power supply. Try it at 24VDC and you may find that is plenty and your motor will stay below 70C.

Mariss

Well I'm sure glad I started asking questions before doing anything. Albeit a little later then I probably should have but none the less I am where I am now.

Mariss I'm a touch confused about this whole voltage thing now. I was checking out the manufacturer spec sheet and on there graphs they are listing 70V 48V and 32V power supply curves. Are these motors not meant to run with 70V power supplies or does something else come into play here? If there not meant to run with these voltages how come there listed there?

[Mariss Freimanis]

Here is a dirty little secret.:-) Motor manufactures want to make their motors look as good as possible. It has been exacerbated by the fierce competition motor manufactures face in this economy.

If I was designing a torpedo I would use the 70VDC speed-torque curve. Heck, I would even use a 200V speed-torque curve and really get something out of the motor before it blew up a minute later when it hit a ship.

You aren't designing a torpedo. You are designing a machine that is supposed to last a few years at least. The manufacturer is supplying you with a "torpedo" speed-torque curve. The manufacturer isn't telling you the motor will melt and destroy itself at 70VDC in short time. What you get is a really cool speed-torque curve without stating the consequences.

You cannot blame the manufacturer because they are against competitive pressures and they leave that little overheating, burning up and melting thing out when they show the graph. Well, on second thought, yes you can blame them. It's devious specmanship.

If you don't believe me, run the motor at 70 VDC. Inside of 15 minutes you'll run screaming your motor is stinking and smoking.

There is no way around the Laws of Physics. Your motor will stink, smoke and burn at 70VDC. To paraphrase Dirty Harry "Do you feel lucky, punk? Do you think you can go for it?" Well, nah, you can't.

Its not just our drive, it's any drive. Your motor will melt, you'll run screaming.

Mariss

[Rift]

Well this is all starting to make a heck of a lot more sense. But I don't think ill be tempting fate on this one.

Do you have any recommendations on a particular power supply other then what I have already found and should be staying away from? Or would the best option still be to construct a custom one?

[Mariss Freimanis]

Standard voltages are 24VDC, 36VDC, 48VDC, 60VDC and 72VDC. Most common are 24VDC and 48VDC. I'd suggest you try 24VDC. The motor you have will get performance beyond what you expect at 24VDC.

Mariss

[Isplat]

I think http://www.kelinginc.net/KL23H276-30-8B.pdf would be a better choice of motors.

Much more in line with the g540's specs.

I'm running similar motors 4-wire vs 8-wire with a 24V based Allegro Chip (Xylotex clone) and get 45IPM in x and 35 IPM in y and 26IPM in Z. I'm limited to 3A by my driver. I have plenty of power. The G540 with double (48V) supply and 3.5A should better my speeds.

If the G540 had been available when I put my system together I would have bought it. In my opinion, it's the best bang for the buck given it's supply voltage, packaging, 4 channels etc.. Nice setup for the Taig and other small mills.

Get a decent 48V switching supply (~10-12A) and you'll be happy. You could use two 24VDC supplies as long as they are "case isolated" at their output. This is a term power supply designers use to indicate that the outputs aren't referenced to the input or the enclosure -- when case isolated, you can think of the output as a "battery" that you can then put in series to get the ~48V you want out of two 24 supplies.

You can run the stepper you bought at the lower 3.5A current of the G540 -- the motors will run, they just won't meet their specs. A different motor would be a better choice....

-Ian

[ChrisPDX]

Sorry to hijack this thread.

I am also looking at a G540 setup with these steppers: http://www.kelinginc.net/KL23H256-21-8B.pdf

and Keling 48V/7.3A power supply

Any opinions on this setup before I order?

Thanks,

Chris

[Rift]

I think http://www.kelinginc.net/KL23H276-30-8B.pdf would be a better choice of motors.

Much more in line with the g540's specs.

I'm running similar motors 4-wire vs 8-wire with a 24V based Allegro Chip (Xylotex clone) and get 45IPM in x and 35 IPM in y and 26IPM in Z. I'm limited to 3A by my driver. I have plenty of power. The G540 with double (48V) supply and 3.5A should better my speeds.

If the G540 had been available when I put my system together I would have bought it. In my opinion, it's the best bang for the buck given it's supply voltage, packaging, 4 channels etc.. Nice setup for the Taig and other small mills.

Get a decent 48V switching supply (~10-12A) and you'll be happy. You could use two 24VDC supplies as long as they are "case isolated" at their output. This is a term power supply designers use to indicate that the outputs aren't referenced to the input or the enclosure -- when case isolated, you can think of the output as a "battery" that you can then put in series to get the ~48V you want out of two 24 supplies.

You can run the stepper you bought at the lower 3.5A current of the G540 -- the motors will run, they just won't meet their specs. A different motor would be a better choice....

-Ian

As far as the drivers go I will have to stick with the G203V's that I have because I bought them from a dealer through ebay who does not accept returns.

Regardless they might be overkill for the Taig but I really don't see any reason why I can't use them while the G540 may be the favorite I'm sure these will work just fine, and I have heard of people using them on this machine.

The motors on the other hand I do have a possibility of getting them exchanged. AutomationDirect seems to have a 30day money back policy. But I'm only going to go through that if its absolutely necessary.

The reason I picked the motors I did was because they had the best inductance of the 3 that I was looking at. From the early information that I was reading people were generally saying lower inductance is the way to go.

Now I'm no expert on this and I have already stated that I'm very new to it, and still have loads to learn. But if there is a fess-able reason for trying to get the motors switched out then I don't have an issue going that route.

But from what I can tell so far I don't see what the issue would be running these motors at less power? Would they not act equivalent to the less powerful models? Its like buying a Ferrari and then going 40mph, (most don't do it) and it was my newbish mistake, but I can still roll around in it and it will work can't I? Provided of course I stick to highways.

[Isplat]

My bad,

I didn't read your original question correctly and as I skimmed some of the rest of the thread, I must have gotten the G540 into my head incorrectly.

This is a smoking setup for the Taig. You'll be fine. If you are using the gecko 203V, the steppers listed, and at least 32-48V PS with enough Amps, you should be fine. Your system should outperform mine... Read no further. Set it up and go...

Basically following "gecko's" rule of thumb calculation for sizing the power supply voltage, I calc you only need about a ~32V.

32 * (√mH inductance) = Power Supply Voltage

32 times the square root of the inductance is your "desired" power supply voltage. For you steppers at 1.18mH that is pretty much 32V (34.76).

I would go with at least 24V supply and preferably a 48V if you can afford it. 48V will give you better performance without violating the "rule of thumb" for P/S sizing by too much. Voltage helps the motors run faster at the expense of heat dissipated in the motor. The more voltage the more heat input to the motor.

I guess the down side of your motor choice was the 5.6A per phase. It requires more Amps of your P/S. Amps * Volts = Watts and Watts = $$.

In my opinion, you want to get a supply that can handle driving all 3 axes at one time. This way you can "rapid" all axes at once without compromise.

If you "undersize" the current your supply can produce, you'll also limit the systems performance.

When buying power supplies there are often "sweet spot" sizes so just try to size your supply amperage close to the needs of all 3 axes. Likewise if you plan to add a 4th axes figure that in to your power supply choice. A simple max would be 3-axes * 5.6A/axes or around ~17A at your supply voltage of choice. This may be "overkill" to some but it will take the P/S out of the equation as a system limit in most cases.

Also, some DC switching power supplies have very “poor” transient response to “load” changes (your stepper motor is the load). Each time it steps it changes the “load” the power supply sees. Thus some DC switching supplies aren’t good for stepper motors. So you do need to find a supply other people have used successfully if you want to use a switching style supply. This is often why “linear” power supplies are preferred by some for steppers.

-Ian