Need Help!- Power supply size ??? for Stepper Motors

[wdysf150]

I just purchased 3 - KL23H286-20-8B stepper motors and I am not sure what voltage and amperage power supply to buy. I have read several articles and I am really confused about what size to purchase. I am looking at the KL-320-36 36V/8.8A 110V/220V for $59.95 and I am not sure if thisis the correct choice. Here are the specs for the stepper motor that I bought. I am planning on running them in Bipolar mode.


NEMA 23 BIPOLAR STEPPER MOTOR 425 oz-in, 1/4” Diameter shaft with a flat KL23H286-20-8B (Dual Shaft) Specification Price: $49 Rated Current: 2.8A, Rated Voltage: 4.17V (in Bipolar Parallel)

I bought them from:

http://www.kelinginc.net/SMotorstock.html

[jalessi]

The stepper driver will be the other determining factor in choosing a power supply, what make and model stepper drivers are you going to use?

Higher voltage will run the motors at faster r.p.m.

The amperage requirement would be 2/3 of the total amp draw of the combined motors.

The 8.8 amps is more than sufficient for three of the KL23H286-20-8B stepper motors.

If your stepper drivers can handle more that 36 volts then the voltage will be the limiting factor in r.p.m.

If 36 volts is above the rated voltage of the stepper drives you will damage the stepper drives.


Jeff...

[irving2008]

Run them bipolar parallel for best results

You will need a driver capable of 2.8A/phase so once you have chosen the driver the power supply will be dictated by its capabilities. So you need to choose a driver before deciding on the power supply.

Your steppers in bipolar parallel mode have 6.8mH coils so aim for a driver voltage of up to 80v for max performance, but the voltage will be limited by the capabilities of the driver. More voltage = more torque at the top end of the speed range. The supply you have chosen will work fine with many drivers, but won't get the most out of your steppers at the top end of their speed/torque curve. That may not matter to you, depends on what your requirements are. There is a top end limit determined by the breakdown voltage of the winding but thats usually much higher than any powersupply you'll be likely to use (typically 95v on NEMA23 steppers).

A Gecko540 for example would be a good match for a 48v supply but no more as its rated at 50v but would be slightly under-utilised on a 36v supply. The steppers will, however, run warmer on a 48v supply compared to a 36v.

The current rating of the supply, for 3 x 2.8A steppers, needs to be at least 6A, preferably higher, but no point in going above say 9A as that's wasting money but won't harm anything - the steppers/driver will pull what current it needs.

In short, unless you want the max performance out of your steppers that supply will do a perfectly good job but choose your stepper driver first before finalising that decision.

[tahustvedt]

36 V power supplies can usually be adjusted down to at least 33 V if the controller has a max of 35 V for example. I don't if it's safe to run that close to the max though, which the switching nature of the controller and supply.

[Crevice Reamer]

I recommend that you get the G540. It is the MOST value for your buck, and far cheaper than buying something slightly less expensive and having to upgrade later.

Your K 425 motors have a Best/Max Voltage of 83V. They will get HOT at that voltage, but not TOO hot. I run mine at 72V and they only get warm to the touch. At 50V, they should barely get warm.

These are not the best motors for the G540, but with a 48-50V PSU, they will run well.

CR.

[Crevice Reamer]

Originally Posted by tahustvedt 36 V power supplies can usually be adjusted down to at least 33 V if the controller has a max of 35 V for example. I don't if it's safe to run that close to the max though, which the switching nature of the controller and supply.

Cheap "chopper" drivers cannot safely run at their max voltage, but must be derated by at least 6 Volts because of back EMF. The G540, however CAN safely run at its max 50V rating.

CR.

[wdysf150]

I agree that the G540 would be a great choice. Price is a little steep at $299 bucks. Can someone recommend another driver choice for KL23H286-20-8B stepper motors using KL-320-36 36V/8.8A 110V/220V . I have not bought a power supply yet

[Crevice Reamer]

What are you going to power with these motors?

CR.

[wdysf150]

I am building a cnc router very similar to the one on the site http://www.buildyourcnc.com

[Crevice Reamer]

Do you plan to do actual WORK with this? Or would you settle for a huge paperweight?

That looks like a fairly large router. More than a mill, and to cover that large area with reasonable efficiency, you are going to want the fastest rapids you can get. Cheap chopper drivers are just not going to give that to you. You will be disappointed with performance and end up spending more money to upgrade.

What you will want is a drive that can micro step, but also morph into full step for high speed. You also don't want your drive to blow up easily so you will want short circuit, disconnect protection and idle current limiting for over temp protection.

The BEST solution for your motors and router would be 4 Gecko 203Vs. They cost $148 each, so $592. The V stands for VAMPIRE because they are nearly unkillable.

Now you will also need a breakout board--about $80.

You will need connectors for the motor cables--about $20.

You might as well get a 72V PSU to get the most out of your 83V motors. That will cost $180.

NOW you will need to wire everything together without it looking too much like a plate of spaghetti. Careful though, trouble shooting this wiring can be a pain.

So for $872 you will be all set.

OR you could buy the $299 plug and play G540, which is a junior version of 4 G203Vs. It comes WITH breakout board and connectors. MOST of the troublesome wiring is already DONE internally. You can use the $60 Keling 48V 7.3A power supply.

Total cost $359--And your router will work the way it should.

OR you could spend $180 -$300 for something that WON'T perform adequately. THEN you can spend more money to replace that. Maybe you can waste money on ANOTHER cheap driver first though. THEN your cheap solution will REALLY cost you.

CR.

[LaserImage]

CR is absolutely right. I had a Mechatronics 3 axis board that came with my router. I spent countless hours trying to tune it to get 30ipm out of it without stalling. Finally, when the X axis stopped working I bought a G540. I get 130ipm with the Gecko and it works absolutely flawlessly. I wish I would have bought it when the Mechatronics first started acting up, but I didn't want to spend the money - what a mistake that was!

$300 may sound like a lot, but when you itemize it out like CR did you can see how it makes $ sense. When you actually use it you will see that it is one of the best investments you made in your router.

Gary

[Hyrum R]

I've bought me the G540 as well. I already blew out two Xylotex boards. Too bad the G540 wasn't around when I built my first machine. It also runs the motors WAAAY quieter than the Xylotex board ever did, plus I can use a 48V power supply instead of only 24V.