"DC Noise" from power supplies?

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clurgy

Clurgy
Hi Fellow members. I am just finalising my electronics parts list for my CNC router build and a comment was mentioned by one of the suppliers which prompts this topic. He asked what type of power supplies I'm using to power the stepper drivers, and after mentioning them to him (see them here https://oceancontrols.com.au/PSM-027.html (note there are 2 per axis connected in series to supply 72VDC to the drivers)) he said I might get some DC noise finding its way back into the controller which may affect sensors, and possibly the axis' too.

Is there anything to worry about with his comments, or is the Masso controller filtered from any "noise" issues?

Attached is my parts list thus far - let me know if you spot any issues with what's on there or any other comments in general...



Thanks in advance,

Lucas :)
 

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breezy

breezy

Moderator
Lucas,

I was going to answer this in your other post but it is more applicable here.

These PS are NOT suitable for your choice of driver and stepper,
  • Stepper current is listed as max 6A / phase,
  • Driver max current 8.2A at supply voltage 20 to 80 volts.

Power supply is 150W at 36v = 4.1A. Regardless of the fact you wish to place them in series the max current is still 4A which is way below what could be demanded from it by the stepper/driver combination. You need to be looking at a single 80v PS per axis with 600W capability (25% overload) or a common 80v PS rated at 2500W.

I can't say anything about the noise problem mentioned by the salesperson.

Regards,

Arie.
 
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clurgy

Clurgy
Hi Arie, @breezy

Thanks for your response. I had a feeling that was the case. It amazes me that these businesses that have electrical degrees can offer me something that isn't suitable for the application! I will do some hunting for a more suitable power supply now thank you. Aside from the PS, was there anything else on my parts list that raises concerns?

Cheers, Lucas :)
 
A

angelars

AngelArs
2.2KW Huanyang is nice for the VFD but I would never buy an air cooled spindle. Water cooled is the way to go.

I would also recommend getting a filter for the AC.
 
C

clurgy

Clurgy
Thanks for your feedback @angelars

I get mixed responses on air-cooled and water cooled. What is your reasoning for stressing never buy an air-cooled spindle? One comment on the air-cooled spindles is it's a bit noisier, but once you start cutting that noise is overrun by the noise from the cutting tip.

Thanks again, Lucas :)
 
breezy

breezy

Moderator
Lucas,

Air cooled run hot when when you slow the spindle down, water cooled are quieter but don't suffer from overheating. You do need to put a flow switch in the cooling circuit to signal MASSO to shutdown if cooling fails.

Regards,

Arie.
 
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angelars

AngelArs
Quote from Clurgy on June 21, 2020, 2:28 pm

What is your reasoning for stressing never buy an air-cooled spindle?
Click to expand...

It has nothing to do with noise and everything to do with science.

Heat (thermal's energy) is what we call energy which is transferred from one body or region to another.

Air is just a very bad conductor of heat. Water, on the other hand is a much, much better conductor of heat.

Air molecules are just not as dense as water molecules. Simple science.

This is one of the main reasons why water cooled systems are much more effiecient.

Is your cars engine water cooled or air cooled? Yes there are a few air cooled engines but they are much smaller, and generally those engines don't last very long.

What about high-end computer systems? Do they stay with traditional (and cheaper) passive air cooled systems or use water cooling? There is a big reason they use water to cool the CPUs, it simply works better.

You want the water cooled spindle because it will work better for you and last much longer.
 
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angelars

AngelArs
Also, make sure you're using the correct cable to power the VFD. Very common mistake.

And use a EMI Power Filter like this one between the power supply and the VFD Drive;

RSEN-2030L TDK-Lambda Americas Inc | Filters | DigiKey

Order today, ships today. RSEN-2030L – Single Phase EMC/EMI Line Filter 30 A 250VAC - Single Stage Terminal Block from TDK-Lambda Americas Inc. Pricing and Availability on millions of electronic components from Digi-Key Electronics.
www.digikey.com www.digikey.com
 
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clurgy

Clurgy
Thanks for your responses @angelars,
Also, make sure you're using the correct cable to power the VFD. Very common mistake
Click to expand...

What is the "correct" cable to power the VFD? I'm guessing a certain gauge or insulated or both maybe? I want to do this right and am happy to spend the money on the right setup...

Cheers, Lucas :)
 
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angelars

AngelArs
Quote from Clurgy on June 22, 2020, 6:58 am

Thanks for your responses @angelars,
Also, make sure you're using the correct cable to power the VFD. Very common mistake
Click to expand...

What is the "correct" cable to power the VFD?
Click to expand...

That all depends on how many feet you're running your cable from the fuse box.

Also, never use wire made out of Aluminum. Make sure it's solid copper.

The wire you use may be different from what I'll be using here in the U.S.

I'm running my cable around 30' and I'll need 10/2 gauge wire;

 
C

clurgy

Clurgy
Hi Arie @breezy

I emailed the supplier of the steppers, drivers and power supplies and advised your workings of how many watts the PS will need to drive my setup, and this was the response I got...

"Hi Lucas, It's a little more complicated than that. The 6A can be known as a full load capacity. A stepper motor will never require the full Amp ratio to run, and only requires a minimum amount of current to run. The 2 x 36VDC PSU in series I have currently recommended are more than sufficient to run your stepper motor. Feel free to provide me your wiring information so I can assist you further."

Thoughts?

I'm not playing anyone against each other, just trying to ensure I purchase the adequate setup to drive everything and am getting mixed responses haha!

Cheers, Lucas :)
 
breezy

breezy

Moderator
Lucas,

I'm no expert on designing CNC systems and the answer I gave was my opinion based on my electronics training 45 years ago.

Yes the salesperson is correct that the steppers would not be drawing the full 6 amps continuously but there will be times the driver will be required to supply instantaneous bursts of 6 amps depending on the load on the stepper. Also the coils in the stepper are low resistance and low inductance which will result in high delta current.

If you wish to obtain further advice on sizing of PS ask the same question on forums like CNCZone or Woodwork Forum subforum CNC Machines.

Regards,

Arie.
 
cncnutz

cncnutz

CNCnutz
Staff member
Hi Clurgy

Stepper motor choice is difficult and something that you want to get right. It will ultimately determine how well your set up runs.
A few years ago i made a video on stepper motors and also a spread sheet on choosing the power supply to match your motor
You can watch the video and download the spreadsheet from the link below.
I strongly recommend you follow the links also to the Gecko website and read up on stepper motors and how to choose the right size for your machine.
The information in the video is based on the articles on the Gecko site.

https://www.cncnutz.com/2018/03/lets-talk-about-stepper-motors-episode.html

Hope it helps
Cheers Peter
 
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clurgy

Clurgy
Thanks Peter @cncnutz

I used your spreadsheet and confirmed that the PSU's I'm purchasing will be suffice for the stepper / driver setup. Your formula uses the 2/3 of the Amp/Phase sum to come up with a power supply amps figure. Your formula says I need 4.0 amps minimum per stepper, and my power supply will be providing 4.4 amps per stepper.

I have already purchased the Masso G3 and other items from the Masso store, and am about to purchase all the steppers, drivers and PSU's

Thank you all for your input thus far, and no doubt I'll have to annoy you with further questions as the build goes on :)

Cheers, Lucas.
 
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perry

perry
Quote from AngelArs on June 21, 2020, 11:52 pm

Is your cars engine water cooled or air cooled? Yes there are a few air cooled engines but they are much smaller, and generally those engines don't last very long.
Click to expand...

I had an aircooled VW with 120k miles on it. Lasted longer than most other cars I've had.

I generally agree with you, but I also build pretty high end PCs here at work for video processing (we have multiple dual-14 core Xeon workstations with two GPUs and multiple PCIe cards). They're all basic air-cooled designs, on 24/7, and they never overheat. Some of the GPUs may use closed-loop passive heatpipes filled with liquid, but the CPU coolers are stock Intel units, which are just passive heatsinks with a fan on top. With proper design (intake and output fans and good airflow), it's not strictly necessary to watercool unless you're talking about overclocking or pushing the machines beyond their rated specs.

That said, I'm working on getting a 1.5kW water cooled spindle up and running this week - for the sound, not for the cooling. I have a friend whose business is centered on his 5x10 Avid CNC, and it uses an air cooled spindle. He's been at it for years and has had no issues other than the noise.
 
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