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IndustryArena Forum > WoodWorking Machines > DIY CNC Router Table Machines > I smoked my HY VFD a month ago. Here is what happened.
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  1. #1
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    I smoked my HY VFD a month ago. Here is what happened.

    I actually thought it was because I was running my spindle at low speed (12000rpm) with a 43mm bit taking a few mm off my spoil board. I thought, that the spindle had become hot inside and shorted out somewhere because I noticed a "spark" in the air. The outside of the spindle was just slightly warm.

    But sparks are fast, circuit breakers not far behind. The HY VFD, actually caught fire inside. I watched the fire for a wee while (as us men do) before it went out.

    Heres the thing. Immediately after the event (and the fire inside the VFD going out) I disconnected the shielded output lead off the VFD and put a meter on it to see where or if the spindle was shorted. It all measured about 2.5ohms between all phases. Open circuit to ground. Visual inspection of the plug, lead, I am anal I looked. Obviously not enough.

    I bought a new HY VFD. Before I plugged it in, I megga checked the lead with 1000v. I wired the new VFD in, and have run the setup for about 3 hours while I make a new Z Axis (I decided to upgrade my spindle) to accept a larger motor. Yesterday, CRACK, same deal without the fire in the VFD. This time a 6mm bit not even working hard.

    Again, meter on the lead. 2.5 ohms between phases. Pull the plug off, and now I see the issue. This lead, still measures open circuit between phases. Still megga checks fine. Hold it, twist it, keep that 1000v onto it, no problem. But occasionally and thats enough, it has an internal short inside. I guess this is "hey look what happened to me". I am not concerned today I am going to install a new plug to see if my setup still runs. The VFD powered up yesterday without the motor connected. Strange that the short is intermittent but thats life.

  2. #2
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    Re: I smoked my HY VFD a month ago. Here is what happened.

    Quote Originally Posted by boydage View Post
    I actually thought it was because I was running my spindle at low speed (12000rpm) with a 43mm bit taking a few mm off my spoil board. I thought, that the spindle had become hot inside and shorted out somewhere because I noticed a "spark" in the air. The outside of the spindle was just slightly warm.

    But sparks are fast, circuit breakers not far behind. The HY VFD, actually caught fire inside. I watched the fire for a wee while (as us men do) before it went out.

    Heres the thing. Immediately after the event (and the fire inside the VFD going out) I disconnected the shielded output lead off the VFD and put a meter on it to see where or if the spindle was shorted. It all measured about 2.5ohms between all phases. Open circuit to ground. Visual inspection of the plug, lead, I am anal I looked. Obviously not enough.

    I bought a new HY VFD. Before I plugged it in, I megga checked the lead with 1000v. I wired the new VFD in, and have run the setup for about 3 hours while I make a new Z Axis (I decided to upgrade my spindle) to accept a larger motor. Yesterday, CRACK, same deal without the fire in the VFD. This time a 6mm bit not even working hard.

    Again, meter on the lead. 2.5 ohms between phases. Pull the plug off, and now I see the issue. This lead, still measures open circuit between phases. Still megga checks fine. Hold it, twist it, keep that 1000v onto it, no problem. But occasionally and thats enough, it has an internal short inside. I guess this is "hey look what happened to me". I am not concerned today I am going to install a new plug to see if my setup still runs. The VFD powered up yesterday without the motor connected. Strange that the short is intermittent but thats life.
    For starters you have the incorrect cable for the VFD Drive to the Spindle you should not have an open Ground cable, this needs to be a 4 wire shielded cable

    Is the Spindle plugs 4th Pin have Ground continuity to the Spindle body, most are not connected inside and this need to be corrected
    Mactec54

  3. #3
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    Re: I smoked my HY VFD a month ago. Here is what happened.

    ...Plugs are always a weak point. get rid of it if possible.
    https://www.google.com/search?client...terminal+strip

  4. #4
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    Re: I smoked my HY VFD a month ago. Here is what happened.

    I made this lead about 8 years ago. Its a 3 core 15A extension cable, and also a single 2.5mm green conductor that I used for an earth. This I pushed through a SS braid to encase the 4 conductors. So in effect, the phase wires are double insulated, and in my mind shielded.
    The ss shield and green wire, green is connected to the earth pin on my new spindle.

    Earth is common throughout the whole machine, right back to the live earth I have next to my main meter box. I have bonding leads to the nana. I am pretty confident it is well earthed and shielded. I also have a filter. I should throw up a pic. The short inside that plug was phase to phase. Actually I will throw up a pic, if I have done something wrong its good to know.

    Hey out of interest - the settings I put into that new spindle. The last one off memory was 120 - 120 anti stall protection. I was unable to stop the spindle. I set it down to 100 to also find I was unable to turn the spindle off. So I set it to zero. What do you reckon?

  5. #5
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    Re: I smoked my HY VFD a month ago. Here is what happened.

    Oh. And to note,I have installed a new spindle. Much nicer plug. They call it an aviation plug but in the 11 years I was a lame I never saw one like it ha. But it was a good one.

  6. #6
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    Re: I smoked my HY VFD a month ago. Here is what happened.

    Quote Originally Posted by boydage View Post
    I made this lead about 8 years ago. Its a 3 core 15A extension cable, and also a single 2.5mm green conductor that I used for an earth. This I pushed through a SS braid to encase the 4 conductors. So in effect, the phase wires are double insulated, and in my mind shielded.
    The ss shield and green wire, green is connected to the earth pin on my new spindle.

    Earth is common throughout the whole machine, right back to the live earth I have next to my main meter box. I have bonding leads to the nana. I am pretty confident it is well earthed and shielded. I also have a filter. I should throw up a pic. The short inside that plug was phase to phase. Actually I will throw up a pic, if I have done something wrong its good to know.

    Hey out of interest - the settings I put into that new spindle. The last one off memory was 120 - 120 anti stall protection. I was unable to stop the spindle. I set it down to 100 to also find I was unable to turn the spindle off. So I set it to zero. What do you reckon?
    That can work if the shield is covered if not the shield can cause some nasty shocks if you touch it at the wrong time, it's not advisable to use a shield that is not covered

    Setting the anti stall parameter has nothing to do with how the spindle turns off, and it must be set to a number that is safe for your spindle 120% is max for these spindles, 0 would give you no protection

    Yes that is quite common to get a short between 2 phase in these plugs, if you have not wired it correctly, you did not say you had a short in your first post

    So you got away with it for 8 years if it had been correctly wired it would most likely been still running for many more years to come
    Mactec54

  7. #7
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    Re: I smoked my HY VFD a month ago. Here is what happened.

    "So you got away with it for 8 years if it had been correctly wired it would most likely been still running for many more years to come"

    Darn. There was a time I thought you might be the VFD guru. After that statement, now I dont.

  8. #8
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    Re: I smoked my HY VFD a month ago. Here is what happened.

    Quote Originally Posted by boydage View Post
    "So you got away with it for 8 years if it had been correctly wired it would most likely been still running for many more years to come"

    Darn. There was a time I thought you might be the VFD guru. After that statement, now I dont.
    Your Ignorance has the best of you, it would help to educate yourself on the subject before you hurt someone or yourself

    Electrical extension cord is not suitable for a 3Phase VFD to Spindle connection and would not meet code requirements

    You megger checked a cable at a 1000v that would not of been rated for a 1000v I'm sure that would of showed leakage after 8 years of use with the VFD Drive, it should of been replaced with the correct cable but ignorance takes over and you know best which does not bother anyone here just paints a picture of who you are
    Mactec54

  9. #9
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    Re: I smoked my HY VFD a month ago. Here is what happened.

    Quote Originally Posted by boydage View Post
    Oh. And to note,I have installed a new spindle. Much nicer plug. They call it an aviation plug but in the 11 years I was a lame I never saw one like it ha. But it was a good one.
    If that is the new plug, then it sounds like it might be a MS (Military Style) connector, normally very $$$ pricey to purchase!
    Part No's are preceded by MS.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

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

  10. #10
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    Re: I smoked my HY VFD a month ago. Here is what happened.

    It Has to be right --- I saw it on the INTERNET !!!!!!!!!!!!!!!

    Don

  11. #11
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    Re: I smoked my HY VFD a month ago. Here is what happened.

    Hi boydage,

    I use about 10 of these in my factory. We face issues with the connectors once in a while.

    The photo you've shared appears to be the same issues we've faced. Whenever we face this we replace the connector on the spindle as well as on the cable and things become OK with that. If we do not change the connectors on either side we end up with repeat failures as you have.

    Best of luck!

    Jaideep

  12. #12
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    Re: I smoked my HY VFD a month ago. Here is what happened.

    Quote Originally Posted by Al_The_Man View Post
    If that is the new plug, then it sounds like it might be a MS (Military Style) connector, normally very $$$ pricey to purchase!
    Part No's are preceded by MS.
    Al.
    They could only wish that they where MS quality connectors, they are a very poor copy of what is known as aviation style connectors you can buy them for around a $1 each shipped
    Mactec54

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