New Machine Build Earth and negative bus bars on a build do I isolate them or common?


Results 1 to 5 of 5

Thread: Earth and negative bus bars on a build do I isolate them or common?

  1. #1
    Member
    Join Date
    Jun 2013
    Posts
    166
    Downloads
    0
    Uploads
    0

    Default Earth and negative bus bars on a build do I isolate them or common?

    Hey so Mach 3 works on the probe (and other) circuit by using the spindle as a make or break against a touch point.

    Im rewiring my machine. We have several voltages being 5vdc, 12vdc, 60vdc. So what happens if I make the negative common among all of these these? So thats also two separate switching power supplies being the 12 and the 60.

    Also, I have shielded my spindle power (between inverter and motor) cable. And will be earthing it to the frame of my machine, along with the shields of the encoder cables.

    Final run, the negative of my sensors, the shields, the earth of the control box and the earth of everything else is going to be common. I dont know if thats going to be a problem or not to address.

    My VW has a special "sensor earth" What do you guys do? B

    Similar Threads:


  2. #2
    Community Moderator ger21's Avatar
    Join Date
    Mar 2003
    Location
    Shelby Township
    Posts
    35138
    Downloads
    1
    Uploads
    0

    Default Re: Earth and negative bus bars on a build do I isolate them or common?

    My opinion is that the VFD should be in the control box. Everything in one box.

    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)


  3. #3
    Member
    Join Date
    Jan 2005
    Location
    USA
    Posts
    11559
    Downloads
    0
    Uploads
    0

    Default Re: Earth and negative bus bars on a build do I isolate them or common?

    Quote Originally Posted by boydage View Post
    Hey so Mach 3 works on the probe (and other) circuit by using the spindle as a make or break against a touch point.

    Im rewiring my machine. We have several voltages being 5vdc, 12vdc, 60vdc. So what happens if I make the negative common among all of these these? So thats also two separate switching power supplies being the 12 and the 60.

    Also, I have shielded my spindle power (between inverter and motor) cable. And will be earthing it to the frame of my machine, along with the shields of the encoder cables.

    Final run, the negative of my sensors, the shields, the earth of the control box and the earth of everything else is going to be common. I dont know if thats going to be a problem or not to address.

    My VW has a special "sensor earth" What do you guys do? B
    Don't get your auto wiring involved with your AC wiring Auto wiring is completely different

    It will depend how noisy the Mains Ground is and how you do it, does your Breakout Boards like the commons to be Grounded or isolated, just remember the supplied power has to return to where it came from and that is your power supplies it can still have a return path and be Grounded as well

    Your spindle and VFD Drive need to have a Ground wire so the cable should be 4 wires Plus a shield , the Main supply what ever it is 230v/240v that Ground also must connect to the VFD Drive

    Mactec54


  4. #4
    Member
    Join Date
    Jun 2013
    Posts
    166
    Downloads
    0
    Uploads
    0

    Default Re: Earth and negative bus bars on a build do I isolate them or common?

    Gerry mate how do you do it with your VSD? Like, did you put a couple of buttons and a 10k pot on the door of your enclosure? Or did you extend the ribbon of the removeable control panel on the VSD and put it on the front? (just guessing its the same as mine)

    Also - do you control the spindle with Mach 3? I am thinking about doing that too if I get this done.

    I have rewired my machine..... now I am thinking I will do what you reckon. Am already halfway there.

    And this is a note for EVERYBODY who needs to go out and buy some wire. Definitely search around for a mate who is in the electrical industry and get them to get your wire or put it on their account if you can. The discounts to trade are absolutely huge. I **** you not. I dont know why the wire retailers put such a botty reaming margin on wire, but they do.



  5. #5
    Community Moderator Al_The_Man's Avatar
    Join Date
    Dec 2003
    Location
    Canada
    Posts
    23482
    Downloads
    0
    Uploads
    0

    Default Re: Earth and negative bus bars on a build do I isolate them or common?

    If you are using a VFD with a CNC system, then it makes most sense to control the VFD with the controller.
    For grounding commons, there is two schools of thought, my preference is to take all power commons to the earth ground star point, so far it has served me well.
    BTW, as to wiring conductors, make sure they are stranded! TEW/MTW etc.
    I prefer TR64 which has a much smaller insulation thickness but still meets voltage requirements, does not take up all the room in wire duct etc.
    Get a copy of NFPA79, there is a copy out there in PDF if you Google it.
    Al.

    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.


Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  


About CNCzone.com

    We are the largest and most active discussion forum for manufacturing industry. The site is 100% free to join and use, so join today!

Follow us on


Our Brands

Earth and negative bus bars on a build do I isolate them or common?

Earth and negative bus bars on a build do I isolate them or common?

Earth and negative bus bars on a build do I isolate them or common?