Motor Driver Electrical Question

Hello All,
I am currently driving my stepper motors via DMT556T's with a 48vdc source.

The motors are from Stepper-Online model 23HS45-4204S .
They can handle 4.2A based on the specs provided.

The current settings offered by the DMT556T are as follows:

 

My question, which Peak Current setting should I be using?

Your driver is technically too small.

4.2A motor current means 4.2A RMS, or about 6A peak.

Peak current is the RMS current multiplied by √2 (approximately 1.4).

You should set your driver to the highest current (5.6A peak).

Your motor won't be quite as powerful as it could be because the current is a bit too low, though you'll probably be fine.

Also, your driver will be working at its maximum rated current, so it will get quite hot, though you should not encounter any problem.

If you find that your motor is too weak, consider buying these drivers:
www.aliexpress.com/item/1005005291871448.html

What is your motor driver?

Is it a genuine Leadshine DM556? (probably not)

Because there is such a vast array of clones of that driver, you should post the link to the exact one you bought.

Also, 48VDC is only 2V away from the driver's maximum voltage of 50VDC, which is not great.

If you can reduce their supply voltage by even a few volts, you should do so to make sure your drivers don't get damaged.

The motors and drivers were part of a kit that included power supply, drivers and Nema 23's that I bought directly from
Stepper Online.

Here's a link to the DM556T drivers which were part of the kit. I could not find the kit online at this time.

On the Stepper Online web site I note the following documentation:Therefore, when setting the current on the stepper motor driver, please try to make the rated current of the motor close to the RMS value of the driver. If the motor needs to work continuously for a long time, you need to pay attention to the temperature rise of the motor. If you feel that the temperature of the motor is too high, you can properly reduce the current.In our experience, we usually match the RMS value on the driver to the rated current of the motor to ensure higher performance. When we feel that the motor is overheating, we match the rated current of the motor to the PEAK value on the driver.Additionally, under short-term working cycle conditions, we recommend using the RMS value, and under long-term working cycle conditions, we recommend using the PEAK value. This document is located here.

Honestly I see no reason why these motors can't be run at 48vdc.

Wow.

I can't believe they sold you undersized drivers in a kit.

Not cool.

Cheapskates.

tommylight wrote:

Set them at 2A and test, see if that is enough for what you need, if not add more in steps and test again.
And while testing, every 10 to 15 minutes do check the motor temperature with your hand, they might get warm and they might get hot and that is ok, as long as you can keep your hand on the motor all is good, and even when it feels it burns like hell, they are still OK, but you might want to lower the current a bit.

There is no 2A setting though, only 1.8A peak or 1.9A RMS.

Take a deep breath, remain calm and read the stepper motor stuff by gecko

www.geckodrive.com/support/


This one is rather enlightening regard power draw and such
www.geckodrive.com/support/power-supply-basics/


I've had my mill setup for that long, using KL5066 drivers (no longer available) max PSU is 50v and I've been running them for years, 10+, on 48v with no ill affects. I think the motors are set for 4 or maybe 4.5 amp I thought I'd add I've run them on days where its been +35'C outside no idea what it's been in the workshop.....no issues

Don't overcomplicate this. The motor is good for 4.2 amps. Set the driver to give it 3.8 amps which is the closest you can go without going past the motor rating. 48 volts will be fine. I've driven similar motors at 90 volts. CNC does not drive motors at peak load for long periods.

Look at the motor's full data sheet www.omc-stepperonline.com/download/23HS45-4204S.pdf
The insulation is rated for 130 deg C so don't let it get hot enough for it to melt as that will destroy your drive. 
The maximum temperature rise permissable is 80 deg C. Add that to 30 deg ambient temp (heck its been up to 39 degrees C here the last week or so). So 80+30 = 110 deg C which is hot enough to burn you but not melt the insulation. If the motor misses steps and it will only do that if it gets too hot (it will then let you know that its missing steps in a spectacular way).

If the drivers have a fault output, connect it to joint.N.fault-in. This will trigger if the motor gets too hot and stop Linuxcnc
If the drive misses steps or faults, reduce the curent to the next lower setting.

Don't be concerned about lowering the current if you need to. The actual current required for a given application may be well below the rated current if you do do a full design. eg one of my 2 amp motors only needs 1 amp to achieve 60 m/min rapids and > 5 m/sec/sec acceleration (tested to 8 m/sec/sec)

Typically, the Chinese drivers are rated based on peak voltage. Some Drivers (eg Lam Technologies) are rated for RMS so a 6 amp driver of theirs will give 6 amp RMS, enough to melt the average Chinese motor. So a 4.2 amp motor is probably run at 2-3 amps with Lam. This is why Tommy suggests a more conservative approach than me!

Ignore all other advice you have been given by others and just do it!

 

rodw wrote:

Ignore all other advice you have been given by others and just do it!


 

Yeah I'd second that.