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Author Topic: Which wires in the control box should be shielded?  (Read 194 times)

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Which wires in the control box should be shielded?
« on: August 24, 2020, 05:57:51 PM »
I understand wires that send info need to be shielded, because one doesn't want the message to be corrupted. 

But how about those that only supply power?  And what about having shielded wire, but then there there can be that last half inch that is not shielded because it is part of a four strand shielded cable? 

How far away from the stepper control stuff should the inverter be?  I imagine it puts out a big chunk of magnetic fields. 

What about the Z axis motor being so close to the spindle?  Do those 4 wires to the stepper motor need every mm shielded?

I want to make it's not EMI that us causing me issues. 

Offline Tweakie.CNC

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Re: Which wires in the control box should be shielded?
« Reply #1 on: August 25, 2020, 01:29:10 AM »
It’s not an exact science so there are differing opinions but here is my take…

All signal inputs (Estop, limit and home switches, probe, etc) should be connected with good quality shielded cables with the shield connected to a single point, ‘star’, Earth at the controller end only.

There should be no ‘Earth loops’ or ‘GND loops’ anywhere in the system wiring.

The VFD inverter should, if possible, be located away from any input wiring or un-shielded electronic circuitry.
The cable between the inverter and the spindle should be shielded with the shield connected to Earth at one end only.
The VFD should ideally have an RFI filter fitted in series with its mains input.
The VFD manufacturer’s instructions regarding earthing / grounding (assuming they are supplied) should be followed.

Stepper and power wires do not need to be shielded unless there are special circumstances.

The last ½ inch or so of un-shielded cable is seldom a problem and should not be of any concern.

Tweakie.
KEEP SAFE !
Re: Which wires in the control box should be shielded?
« Reply #2 on: August 25, 2020, 11:36:26 AM »
Tweakie,

It's hard to quantify how helpful you are.  Thank you.
Re: Which wires in the control box should be shielded?
« Reply #3 on: September 24, 2020, 09:52:31 AM »
Change the state of Probe pin (if Unchecked Active Low check it, and vice versa). i did no work  maybe i need to ground the chassis where BOB is 
Re: Which wires in the control box should be shielded?
« Reply #4 on: September 24, 2020, 10:08:42 AM »
mikec here i fixed it mach3 general config go to de bounce it was at 0 i set it to 150 it stop tripping the limit switch
i must have alot of noise thanks for your help.