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Author Topic: VFD in box or not  (Read 265 times)

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Offline mark4

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VFD in box or not
« on: October 28, 2019, 06:52:51 PM »
Hello I see lots of panels with VFDs mounted in them. And yet VFDs are noisy so that would say keep them away from motion control and drives. Anyhow I want you opinion on weather to put it in a box or not and if you ever had trouble.
thank you
Mark

Online thosj

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Re: VFD in box or not
« Reply #1 on: October 28, 2019, 06:58:49 PM »
Mine is NOT in the box, maybe 4 feet beside/behind/above the control box. Originally I didn't have room IN the box so couldn't have squeezed it in if I wanted to, and now that I've rebuilt the box with much more room, I didn't move the VFD. It's in it's own metal box but NOT in the box with the rest of the stuff. Seems like the way to do it to me, but I've seen pics of lots of boxes with the VFD in them, so............maybe? Noise is tricky to track down, so my opinion is NOT in the main box.

Tom
Re: VFD in box or not
« Reply #2 on: October 28, 2019, 08:22:19 PM »
before i use mach ,i use to use TPA ,its Italy controller ,then we had a lot of trouble
now when i use mach with pokeys ,i dont have any prolem with the inverter
pokeys have separate  ground to connect the inverter as 0-10 v
maybe this also help to avoid noise come into the system


Offline smurph

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Re: VFD in box or not
« Reply #3 on: October 30, 2019, 12:14:05 AM »
Most manufactured machines from "back in the day", like my Matsuura MC500V, had two cabinets on them.  One for the control/drives and one for the VFD (and other less sensitive wiring).

Steve
Re: VFD in box or not
« Reply #4 on: October 30, 2019, 08:50:13 AM »
I do a lot of work day to day with VFD drives. You CAN place them in the cabinet with your controls, but you need to be very diligent about following proper grounding and EMI mitigation practices. This includes having a galvanized or SS subpanel in your enclosure (or removing the paint from under your VFD), having a master grounding bar with braided grounding straps going to each subpanel, grounding the enclosure body individually, etc. Physical separation of AC, DC and VFD output wires is a must to prevent noise from coupling onto your control wires.

Even then you do risk having issues with noise. If you do place your VFD in another box, you really should still be following all these practices. Shielded cables are a lifesaver, but can get a bit expensive.

Offline Chaoticone

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Re: VFD in box or not
« Reply #5 on: October 30, 2019, 08:59:48 AM »
I do a lot of work day to day with VFD drives. You CAN place them in the cabinet with your controls, but you need to be very diligent about following proper grounding and EMI mitigation practices. This includes having a galvanized or SS subpanel in your enclosure (or removing the paint from under your VFD), having a master grounding bar with braided grounding straps going to each subpanel, grounding the enclosure body individually, etc. Physical separation of AC, DC and VFD output wires is a must to prevent noise from coupling onto your control wires.

Even then you do risk having issues with noise. If you do place your VFD in another box, you really should still be following all these practices. Shielded cables are a lifesaver, but can get a bit expensive.

Bravo! EMI can be the biggest pain imaginable. Best to do all you can to mitigate it as building rather than redoing IMO.

I prefer the VFD in it's own metal (ventilated/cooled is important) enclosure. This way if done right it has it's very own personal faraday cage. I have put them in cabinets with other components but never would if I could avoid it.
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!

Offline mark4

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Re: VFD in box or not
« Reply #6 on: October 31, 2019, 12:38:29 AM »
Thank you for your input. I have this to add. I am upgrading the controller also. This is going on a lagun mill and I have seen something I have never seen before. I have a wiring diagram and I find this wire #1 goes to the neutral of the 110vac transformer and the same #1 goes to all 0v on the 24volt dc power. it is the damnest thing I have looked and looked and it is wired just like that. I am planning to separate ac neutral and 0vdc just for my own sanity.
Mark