DIY CNC Milling Machine From Scratch

[totts]

So you have USB shield earthed at box end and the vfd earthed there too? Have you a shielded cable from ur vfd to motor?


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[Boyan Silyavski]

I have all earthed at box body -PC, all Transformers inside, etc. The VFD is outside, just near the box. Yes it has screened cable to the spindle connected both ends. So it's connected to machine. Machine is also connected to box. So all also is grounded together at socket. Go and figure then why problems disappeared when i connected VFD box with big box. In other words- they were grounded at socket and machine prior to the bypass cabling that solved problems.

I could only say that my stupid persistence lead to a result. I was many times at point of taking my big hammer and ...

[nairepooc]

All this talk of Grounding and Earthing, is making me even more confussed!
Is Grounding connecting to 0V dc and Earthing to a Star earthing point or am I missing something, or are we mixing up the terms?

[Clive S]

All this talk of Grounding and Earthing, is making me even more confussed!
Is Grounding connecting to 0V dc and Earthing to a Star earthing point or am I missing something, or are we mixing up the terms?

Grounding and Earthing often creates a lot of confusion and to some extent depends how old you are. But you don't connect your DC ground to the Star point which is the point where all the screens connect to and then that is connected to the AC earth. The reason for the Star point is to get rid of earth loops (or ground loops if you are old).

Sometimes you have more than one DC power source and again somtimes you have to connect the various DC power -ve together. Hope this helps a bit.

[Boyan Silyavski]

Sorry, my mistake then. In my mother language -ground and earth is the same word, not 2 different. So when i say Ground or Earth, i mean the same. Stick 2m long in the ground that is connected to all grounds in house line electricity, mind not the 0 or phase. If we are talking for DC i say Negative or Common ground. I am not sure that's right, but as English is not my native language ...

[Davek0974]

Dictionary wise both are same.

But in electrical engineering context both words differ in scope. Ground is a general term that refers to a reference potential against which all voltages are measured. Earth is same as ground but used in context of power systems because the ground here is implemented by burying copper conductors deep down into Earth.

Since Earth has minerals, moisture and it has practically infinite volume, the current flow is only limited by contact resistance between ground/earth conductor and soil. Because of this, on the distribution side, the neutral is connected to earth. On receiving side, fault current from one of the phases can flow into the local earth conductor and make its way to the neutral at distribution side. Apart from being a sink for fault current, the Earth conductor also serves as a return path for instrumentation systems.

:)

[njhussey]

Dictionary wise both are same.

But in electrical engineering context both words differ in scope. Ground is a general term that refers to a reference potential against which all voltages are measured. Earth is same as ground but used in context of power systems because the ground here is implemented by burying copper conductors deep down into Earth.

Since Earth has minerals, moisture and it has practically infinite volume, the current flow is only limited by contact resistance between ground/earth conductor and soil. Because of this, on the distribution side, the neutral is connected to earth. On receiving side, fault current from one of the phases can flow into the local earth conductor and make its way to the neutral at distribution side. Apart from being a sink for fault current, the Earth conductor also serves as a return path for instrumentation systems.

:)

Look who swallowed a dictionary.....nice clarification, cheers Dave 😊