EMI and Grounding Loops?


I’m about to upgrade my 2015 X-Carve ( X-Controller ) with a 1.5kW HuanYang GT VFD and matching 0.8kW HuanYang Water Cooled Spindle.

Reading through some of the threads covering VFDs I came across the issues of EMI and Grounding Loops which might be a thing with my cramped setup since every piece of electronic in my basement will be run off a single 220V power outlet - That will be the PC ( or Laptop ), X-Controller, VFD & Vacuum.

Concerning the EMI I was thinking about buying a quality shielded cable and not running it along the other wires of the machine but instead along the wall / ceiling and then hanging it down towards the Spindle with enough slack for the head to reach all corners of the machine without issues ( maybe support it with a wire attached to a spring mildly keeping it on tension? )

As for preventing grounding loops I was thinking of connecting the PC to the X-Controller using an Adafruit USB Isolator?

Controlling the VFD via the X-Controller appears to be done using a 4 wire connection - 2 to turn on/off the spindle ( requiring a 1 Channel Relay Shield Module ) and another 2 to set the RPM which both appear to cause an electrical connection and possible grounding loop - Anything that can/should be done about this?

Speaking of 1 Channel Relay Shield Module… These buggers appear to require a 5V Power Source coming in from the X-Controller side - Where would one usually get those 5V from? Off an internal connection from the X-Controller or a 5V Phone Charger / 5V Power Supply?

Any other precautions you’d recommend or advices?

Limited space and a single outlet doesn’t cause EMI. Bad grounding does.

Yes this will help. You’ll need at least 2 -3 inches of space between the cable runs.
Quality cable = 16/3 with ground double shielded. Both Belden and IGUS (CF6-15-04) make good cables for this.

Not the best idea. Use a EMI Filter power filter. The TDK RSEN-2030L is one example.

Use the “star” grounding method. No pigtails. And take the top of the HuanYang spindle off and properly ground pin #4.

Thanks for the in detail reply!

Bunch of questions regarding your recommendations though:

  1. Which device would be hooked to the RSEN-2030L Powerline Filter and why this ( 30A ) model in particular?
    Out of the blue, I’d assume it’s supposed to be installed on the 230V line feeding the VFD Inverter since it connects back to all the other devices?
  2. Star Grounding is what I believe I’m using it on my 230V Lines feeding all Devices but what’s Pigtail Grounding?
    I wasn’t able to find anything on the iNet with that name that would have made sense given the context.

Thanks in Advance! =)

You don’t need to use the 30A model unless you are running the 110 volt/1.5kw VFD. They make many models and other companies do as well.

It needs to be installed directly into the VFD, with nothing between it and the VFD.

You see a lot of pigtail grounding with connectors. For example, someone might take the shield and connect it to pin 4 of the spindle plug. Pigtail grounds are not good practice and have been known to induce EMI.

Grounding Shields-7

Yeaaa… I don’t think that installing the Powerline Filte into the VFD Inverter is an option unless you assume the VFD was installed inside a metal enclosure and you’re suggesting the installation of the Filter AND the VFD inside that housing.

I guess installing a Filter would then only be possible between the VFD and the 230V distributor that connects it to the Power outlet and all the other Hardware ( Laptop, X-Controller, 12+5V PSU, etc… )?

I guess I have to admit of being guilty to the charge of pigtailing the Shielding Wires >_>
Both the Control and Spindle Cables have had their Shielding pigtailed and grounded to the 230V Grounding Wire.
I have absolutely no idea how to do otherwise as the VFDs Housing is ( obviously? ) not conductive so none of the suggested methods in your picture would work without that being the case?

So, now I am intrigued…what benefits do you get from these upgrades please? What does a VFD do for us coupled with the spindle?

  • 8’000-24’000rpm range compared to the DeWalt 611s 16’000-27’000rpm which makes it REALLY nice for plastics.
  • Uses Industry-standard ER-11 Collets.
  • Automatically start and stop the Spindle at the beginning and end of an operation.
  • RPM will automatically be set and forget via a Tool Library that automatically ships with the G-Code the machine works with.
  • Live adjustment of RPM in the Controller Software when something sounds weird.
  • IMHO, less noisy than a brushed Router ( DeWalt 611 ) which, IMHO, makes a difference despite the noise coming from the cutter digging into the material.
  • Practically no maintenance requirement unlike a brushed Motor requiring new brushes every once in a while.
  • No fine dust getting blasted all over the place due to lack of active cooling at the spot the cutter is working - This though only applies to the Water Cooled variants.

Except for the widened RPM Range mostly just quality of life things but hey… They add up in the long run =)

You don’t install the filter “in” the VFD.

You install it inline, just before the VFD.

You would use a shield clamp for these. One example is shown below;

Many, many benefits. As mentioned above and something that most people overlook until they have the pleasure of using a water cooled spindle, is that generally electric routers (Dewalt, Makita, etc.) are air cooled, which pushes air downwards through the router to cool the router motor. This has an undesirable effect with CNC machines because they will blow the dust and chips that you cut into the air. The water cooled spindle cannot blow your chips around because it uses water to cool the spindle motor. This allows the chips and dust to be confined within the dust shoe area and get removed by the vacuum much more effectively.

Additionally, standard routers are very loud, and their sound level far exceeds that of any water cooled spindle. They also generally have a lot more torque than electric routers. Plus because water cooled spindles use precision bearings and a more balanced collet, it will minimize run-out resulting in superior performance. When an electric router is cutting it looses RPM which can result in damaging the material being cut. Water cooled spindles do not have this issue. Most water cooled spindles VFD draw less current, so it cuts down on operating cost. There are many benefits of using a water cooled spindle. Only downside is having power routed to the VFD, but that is easily solved and is straight forward once you decide what size to buy.

I’ll be having a look into the recommendations and see how it goes - Thanks a lot! :wink:

Don’t forget to add a couple of Ferrite Toroids / Ferrite Rings on the output wires of the VFD. They will help a LOT to reduce EMI and are fairly cheap. This video helps to show how they work (Fast forward to 21:34);

BTW, this book covers the topic in detail;


There is lots of great information located here as well;