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IndustryArena Forum > CNC Electronics > Spindles / VFD > Chinese VFD mains power wiring
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  1. #1
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    Chinese VFD mains power wiring

    Hello,

    I have made a mistake and cheaped out on the inverter. Now I am trying to wire it and it is not clear where should I put earth from the wall plug and where should I put the earth from the spindle.

    The model number of the vfd is A2-8022 and it is made by Isacon Power Control Tech.
    I have 7 port on the spindle, 3 (RST), there is a green sign in the middle that I think maybe the earth, and there is UVW on the right side. In the manual it is written that for one phase 220 V I should connect R and T as it is seen in the picture. As i know UVW is for the 3 phase of the spindle, but I am not sure about the earth.

    Should I connect both earth wire to that terminal?

    I read different opinions on the earth wiring on these machines, like it is not necessary to connect earth for the spindle and it could cause a loop if I would connect the machine to earth, but I do not think that would happen.
    Also somebody mnetioned that if I do not connect the spindle to earth it could lead to its failure.
    Anyway I am just a hobbyist in low voltage so I am not sure, but I would connect everything to earth if it does not cause any toruble.

    The way I want to do it, is that I would use use 1 wire from the wall to power everything, I would make an earth block in the electrical cabinet and connect everything to it(VFD,spindle, power supplies, the frame and the cabinet). Is that a good solution or is there something wrong with it?
    Attached Thumbnails Attached Thumbnails VFD.jpg  

  2. #2
    Community Moderator Al_The_Man's Avatar
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    Dec 2003
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    Re: Chinese VFD mains power wiring

    As typical with Asian made devices, often the GND is absent or not obvious if there is a GND symbol you should supply a ground conductor also the frame of the motor should be earth grounded.
    The terminal marked GND on the terminal strip is probably just for the internal LV supply common, if so it is not the main ground of the unit.
    Essentially the only thing in these VFD that need earth grounding is the power semiconductor large heat sink, the other is for any suppression device in the main power circuit.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

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

  3. #3
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    Re: Chinese VFD mains power wiring

    Than I guess I will not connect the earth to the VFD, but I will connect the spindle to earth.
    The whole vfd is in a plastic case, so it should be alright, atleast no danger for myself if i ground the spindle.
    Thank you for the information.

  4. #4
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    Jan 2005
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    Re: Chinese VFD mains power wiring

    Quote Originally Posted by Weyla View Post
    Hello,

    I have made a mistake and cheaped out on the inverter. Now I am trying to wire it and it is not clear where should I put earth from the wall plug and where should I put the earth from the spindle.

    The model number of the vfd is A2-8022 and it is made by Isacon Power Control Tech.
    I have 7 port on the spindle, 3 (RST), there is a green sign in the middle that I think maybe the earth, and there is UVW on the right side. In the manual it is written that for one phase 220 V I should connect R and T as it is seen in the picture. As i know UVW is for the 3 phase of the spindle, but I am not sure about the earth.

    Should I connect both earth wire to that terminal?

    I read different opinions on the earth wiring on these machines, like it is not necessary to connect earth for the spindle and it could cause a loop if I would connect the machine to earth, but I do not think that would happen.
    Also somebody mnetioned that if I do not connect the spindle to earth it could lead to its failure.
    Anyway I am just a hobbyist in low voltage so I am not sure, but I would connect everything to earth if it does not cause any toruble.

    The way I want to do it, is that I would use use 1 wire from the wall to power everything, I would make an earth block in the electrical cabinet and connect everything to it(VFD,spindle, power supplies, the frame and the cabinet). Is that a good solution or is there something wrong with it?
    An Earth ( Ground ) is necessary no matter what piece of equipment you are wiring, your thoughts are correct one Ground Bus ( Star Ground Point ) is all that is needed, the input power supply Ground can connect direct to this Bus and all other Ground /Earth wire connections, VFD Drive Power supplies Etc can then all connect to this ( 1 ) Ground point, including your spindle Ground

    Yes the spindle Bearings will have a short life without a Ground so yes Damage can happen to your spindle and yourself the user if it has no Safety Ground / Earth connection

    If you can't find a Earth Ground Terminal connection on the VFD Drive , take the plastic covers off and make a connection on the main body Aluminum Heat sink
    Mactec54

  5. #5
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    Re: Chinese VFD mains power wiring

    Quote Originally Posted by Weyla View Post
    Than I guess I will not connect the earth to the VFD, but I will connect the spindle to earth.
    The whole vfd is in a plastic case, so it should be alright, atleast no danger for myself if i ground the spindle.
    Thank you for the information.
    The VFD Drive must be connected to Earth / Ground
    Mactec54

  6. #6
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    Re: Chinese VFD mains power wiring

    Thank you for the tips, they are life savers
    I forgot to check if that extra symbol is ground or not, but now I checked and it is not connected to the heat sink. I will attach the earth to one of the screws on the heat sink.

    For the stepper motors I am going to buy 5 conductor cables and connect them to earth, so everything should be connected to it.

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