[Pader]

Hi folks,
I am finally getting around to installing my Yuhuan VFD to my chinese, 1.5kW, water cooled spindle.

I have watched numerable YouTube tutorials on the subject but still feel uneasy with the installation. In all of the tutorials that I have seen, the spindle has 4 terminals but mine has just 3 on the Aviation plug at the spindle.

I am aware that the power to the spindle must be through screened cable and I have the requisite length of 3 core cable with a braided screening layer over it. I have checked that there is no electrical connection between the phase pins on the 'Aviation' plug fitted (which is good) and that there is continuity between the Aviation socket and the spindle body.

What I had in mind was to fit a 3 pin aviation plug into the base of the VFD with the pins connected to the three phase connections on the VFD wiring panel and the ground terminal to be connected to the body of the Aviation socket. Then, ground the braiding of the cable to the plug using the cable clamp fixture on the plug.

What I need to know is should I also ground the braid at the spindle end too, or would this give me problems with a 'ground loop' bearing in mind that the body of the spindle would also be grounded by this method?

Perhaps I am looking at it from the wrong perspective and hope that one of you more knowledgeable types can give me guidance.

Thanks in anticipation.

[Al_The_Man]

If you have good earth bonding of the various machine sections, for e.g. earth wire from a moving gantry back to the star point etc.
In all the years of fitting VFD's I have never used screened cable, in fact when VFD's first came on the scene there was no such thing aimed at this application.
I have always used flexible metalic conduit to the spindle which by its nature is grounded both ends, the MTW/TEW wiring used was three conductors twisted together with the earth conductor ran along side them.
This has never ever been a problem for me.
You should find a point on the motor frame in order to use a ground wire point if non is supplied by the manuf..
Al.

[ger21]

Flexible metallic conduit is not an option on a machine where the spindle moves, which is 99% of the machines using these spindles.

[Al_The_Man]

One of the points i was making though is that

What I need to know is should I also ground the braid at the spindle end too, or would this give me problems with a 'ground loop' bearing in mind that the body of the spindle would also be grounded by this method?

is the chance of ground loop is removed by a suitable earth wire to motor frame, then both ends of any shielding can be connected to earth..
Al.

[mactec54]

Hi folks,
I am finally getting around to installing my Yuhuan VFD to my chinese, 1.5kW, water cooled spindle.

I have watched numerable YouTube tutorials on the subject but still feel uneasy with the installation. In all of the tutorials that I have seen, the spindle has 4 terminals but mine has just 3 on the Aviation plug at the spindle.

I am aware that the power to the spindle must be through screened cable and I have the requisite length of 3 core cable with a braided screening layer over it. I have checked that there is no electrical connection between the phase pins on the 'Aviation' plug fitted (which is good) and that there is continuity between the Aviation socket and the spindle body.

What I had in mind was to fit a 3 pin aviation plug into the base of the VFD with the pins connected to the three phase connections on the VFD wiring panel and the ground terminal to be connected to the body of the Aviation socket. Then, ground the braiding of the cable to the plug using the cable clamp fixture on the plug.

What I need to know is should I also ground the braid at the spindle end too, or would this give me problems with a 'ground loop' bearing in mind that the body of the spindle would also be grounded by this method?

Perhaps I am looking at it from the wrong perspective and hope that one of you more knowledgeable types can give me guidance.

Thanks in anticipation.

What you where planning to do would work well, just make sure the exposed Ground wire is as short as possible, at the spindle end, if that's what you are going to do, Braid on the outside of the cable is not recommended, and you need a 4 core any way 3 Hot and Ground Plus shield, IGUS is an ideal place to get good cable, there part number is

You can not create a Ground loop if you wire everything correctly

https://www.igus.co.uk/

This is 16 Gauge Numbers you can use 18 Gauge for your 1.5Kw Spindle

CF35-15-04

CF31-15-04

[Pader]

What you where planning to do would work well, just make sure the exposed Ground wire is as short as possible, at the spindle end, if that's what you are going to do, Braid on the outside of the cable is not recommended, and you need a 4 core any way 3 Hot and Ground Plus shield, IGUS is an ideal place to get good cable, there part number is

You can not create a Ground loop if you wire everything correctly

https://www.igus.co.uk/

This is 16 Gauge Numbers you can use 18 Gauge for your 1.5Kw Spindle

CF35-15-04

CF31-15-04

The picture shows the connection end of my spindle with just 3 pins in the Aviation connector. The black metal cap, body of the spindle and the aviation connector body all have electrical continuity and so I cannot see where a 4th conductor would connect.

In one of the videos that I watched, the maker chose not to connect the ground wire to the motor and the motor functioned perfectly. Am I correct in thinking that the spindle motor is a brushless motor similar in design to those used in model aircraft and do not have a ground connection?

The cable that I have has 3 cores enclosed in a pvc sheath with a closely wound steel wire braiding about it. The whole cable originally had a heavy pvc sheath around it but this I removed because it considerably stiffened the cable making it too stiff for use even inside the cable chains that I am using on my machine for all wiring. I am considering coating the braid with silicone to keep the braiding in place when it flexes.

The braiding outer diameter is just the right size to clamp tightly in the body of the aviation plug providing earth continuity from the body of the spindle all the way through to another aviation plug/socket at the VFD with the body of the socket connected directly to earth on the VFD main panel block.

[Pader]

I am thinking that what you advocate is functionally achieved by what I have written in reply to Mactech54 above. Am I correct?

[Pader]

I would not dream of using flexible conduit in the circumstances that you suggest. I do use it to route cabling on non-moving parts but if they were required to flex often, would result in the spiral casing unravelling. What I am suggesting for use is 3 core flex with a steel wire braiding completely about the cable which will enable sufficient flexure.

[Pader]

If you have good earth bonding of the various machine sections, for e.g. earth wire from a moving gantry back to the star point etc.
In all the years of fitting VFD's I have never used screened cable, in fact when VFD's first came on the scene there was no such thing aimed at this application.
I have always used flexible metalic conduit to the spindle which by its nature is grounded both ends, the MTW/TEW wiring used was three conductors twisted together with the earth conductor ran along side them.
This has never ever been a problem for me.
You should find a point on the motor frame in order to use a ground wire point if non is supplied by the manuf..
Al.

Shielding was recommended to me by the guy from which I have bought most of my equipment. He said it is essential to prevent RF interference to nearby equipment and that he installs it on all of his machines for sale including high end industrial machines. Thank you for your contribution though.

[mactec54]

Shielding was recommended to me by the guy from which I have bought most of my equipment. He said it is essential to prevent RF interference to nearby equipment and that he installs it on all of his machines for sale including high end industrial machines. Thank you for your contribution though.

Shielding is a no brainer, it is a code requirement in some countries

Because you only have 3 Pin Spindle Plug, your best choice, is to remove the spindle plug, and add a cable restraint like in this photo, for this you remove the top of the spindle and wire everything direct, the shield would then be grounded by the cable restraint, and your Ground wire connected like the photo, it is important to get the correct cable restraint gland as some are not for Grounding the Shield

Like this https://hollandshielding.com/EMI-RFI-cable-entry-glands

[mactec54]

Here is another supply for the Cable Restraint Gland, just cut and paste this and it will open as a PDF file, it was too big to down load here

file:///D:/EMF%20Shield%20Grounding/CORD_GRIP_CATALOGUE.pdf