Electrical noise issues AGAIN - External Estop requested...


Results 1 to 16 of 16

Thread: Electrical noise issues AGAIN - External Estop requested...

  1. #1
    Member Chris D's Avatar
    Join Date
    Apr 2005
    Location
    USA
    Posts
    510
    Downloads
    0
    Uploads
    0

    Default Electrical noise issues AGAIN - External Estop requested...

    Hi Folks,

    A few years back I had electrical noise problems like crazy, shielded all the cables, checked all the grounds etc. Then someone recommended a line filter like the one shown in the photo below. Like magic it fixed the problem and has been running 100% reliable for the past several years..

    This past week I started adding some more stuff to my machine ( which is a Router with Mach 3, Warp 9 ESS, 2.2kW spindle motor and VFD). I have added a handful of switches, a couple of solenoids, a stepper driver and motor, etc in an effort to add a tool changer to the machine.

    Now I have electrical noise problems again and am getting these two issues:

    1) Random External E-Stop requested being reported by Mach
    2) Random, very short moves on some of the axis.

    Before I rip everything out to get back to pre-modification state, I am wondering if these (see below) line filters can go bad over time?

    Thanks for any and all help and or suggestions!

    Chris D


    Electrical noise issues AGAIN - External Estop requested...-line-filter-jpg

    Similar Threads:


  2. #2
    Community Moderator Al_The_Man's Avatar
    Join Date
    Dec 2003
    Location
    Canada
    Posts
    23634
    Downloads
    0
    Uploads
    0

    Default Re: Electrical noise issues AGAIN - External Estop requested...

    They don't usually go bad as far as my experience has been, and they are not always a cure-all.
    If you have been adding devices, you may not have observed grounding and bonding, motor frame etc.
    i.e. ensure motor frame is earth bonded.
    Is the VFD supplied from a different source to the Mach3 etc?
    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
    Member
    Join Date
    Jan 2005
    Location
    USA
    Posts
    12074
    Downloads
    0
    Uploads
    0

    Default Re: Electrical noise issues AGAIN - External Estop requested...

    Quote Originally Posted by Chris D View Post
    Hi Folks,

    A few years back I had electrical noise problems like crazy, shielded all the cables, checked all the grounds etc. Then someone recommended a line filter like the one shown in the photo below. Like magic it fixed the problem and has been running 100% reliable for the past several years..

    This past week I started adding some more stuff to my machine ( which is a Router with Mach 3, Warp 9 ESS, 2.2kW spindle motor and VFD). I have added a handful of switches, a couple of solenoids, a stepper driver and motor, etc in an effort to add a tool changer to the machine.

    Now I have electrical noise problems again and am getting these two issues:

    1) Random External E-Stop requested being reported by Mach
    2) Random, very short moves on some of the axis.

    Before I rip everything out to get back to pre-modification state, I am wondering if these (see below) line filters can go bad over time?

    Thanks for any and all help and or suggestions!

    Chris D


    Electrical noise issues AGAIN - External Estop requested...-line-filter-jpg
    What are the voltages of the solenoids Ac or Dc can you post some photos of what you have added and the wiring may just be a simple Grounding of the Drive or twisting the wire pairs may solve the problem

    The power EMI Filter if not mounted in the correct location will not work as well as it should , you may need more than ( 1 ) EMI Power Filter

    The Filter should be ok But there are better Filter than that one

    Mactec54


  4. #4
    Member Chris D's Avatar
    Join Date
    Apr 2005
    Location
    USA
    Posts
    510
    Downloads
    0
    Uploads
    0

    Default Re: Electrical noise issues AGAIN - External Estop requested...

    Quote Originally Posted by Al_The_Man View Post
    They don't usually go bad as far as my experience has been, and they are not always a cure-all.
    If you have been adding devices, you may not have observed grounding and bonding, motor frame etc.
    i.e. ensure motor frame is earth bonded.
    Is the VFD supplied from a different source to the Mach3 etc?
    Al.
    Hi Al The Man,

    The VFD is 220 single phase and is powered independently of the rest of the machine which is powered with 120. However, the VFD is in the same metal box (enclosure) as all the other electronics EXCEPT the stuff that I have been adding which is outside the box.

    Thanks for chiming in!

    Chris



  5. #5
    Member Chris D's Avatar
    Join Date
    Apr 2005
    Location
    USA
    Posts
    510
    Downloads
    0
    Uploads
    0

    Default Re: Electrical noise issues AGAIN - External Estop requested...

    Quote Originally Posted by mactec54 View Post
    What are the voltages of the solenoids Ac or Dc can you post some photos of what you have added and the wiring may just be a simple Grounding of the Drive or twisting the wire pairs may solve the problem

    The power EMI Filter if not mounted in the correct location will not work as well as it should , you may need more than ( 1 ) EMI Power Filter

    The Filter should be ok But there are better Filter than that one
    Hi Mactec,

    I suspect that the EMI Filter's location and quantity would be good if it worked for a couple years before today, that's why I wondered about the possibility it could have died or something.

    As for the solenoids, they are 24vDC and switched with relays. I doubt they are the source of the problem as I can have the machine on all day (as I have been) without any problems.

    The problem ONLY happens when the VFD is ON and the spindle is running (currently only running at 7500 RPM). All the electronics and wiring is currently laying on top of the machine's table going into a non-metallic junction box.

    When you say grounding of the drive. which drive are you referring to? (VFD or Stepper?)

    Thanks for Chiming in!

    Chris



  6. #6
    Community Moderator Al_The_Man's Avatar
    Join Date
    Dec 2003
    Location
    Canada
    Posts
    23634
    Downloads
    0
    Uploads
    0

    Default Re: Electrical noise issues AGAIN - External Estop requested...

    All stepper motor frame and spindle motor should be bonded to earth GND, just to be sure, I would bond the GND that comes in on the 120v as well as one that would normally be with the 240v to each other.
    You should also apply customary wiring and enclosure practices, you cannot expect a machine such as CNC that combines 5v logic with 120vac/240vac power devices without some observation of these practices.
    Look up NFPA79 for a start, this is still available out there in PDF I believe.
    Also ensure that all relay coils have reverse diodes or snubbers across the coils.
    Al. .

    CNC, Mechatronics Integration and Custom Machine Design

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


  7. #7
    Member Chris D's Avatar
    Join Date
    Apr 2005
    Location
    USA
    Posts
    510
    Downloads
    0
    Uploads
    0

    Default Re: Electrical noise issues AGAIN - External Estop requested...

    Hi Al,

    The relays are on a circuit board as a "pre-built" unit stating it has the diodes for protection. I will double check that 120 is also grounded and that it is the same spot as the 220.



  8. #8
    Member Chris D's Avatar
    Join Date
    Apr 2005
    Location
    USA
    Posts
    510
    Downloads
    0
    Uploads
    0

    Default Re: Electrical noise issues AGAIN - External Estop requested...

    Related questions..

    Years back on industrial CNC machines, I recall that they used to keep most of the high powered transformers and power supplies in a separate cabinet from the logic level components. I can't recall if they put the servo drives there too though.

    Being that it is often a fight to get rid of or fix the problems with EMI on these DIY CNC machines, especially those using 5v logic levels, I am wondering if it would be beneficial to place the electronics in two separate cabinets.

    Cabinet #1 :
    Mains input
    Stepper power supply
    Logic power supply (and any others)
    Stepper (servo) drivers
    VFD for the spindle
    Any other high voltage / high frequency devices.

    Cabinet #2:
    PC (If placed in cabinet)
    CNC Controller board (Such as smooth stepper)
    Breakout board
    All logic level connections (limit switches, buttons, sensors, etc.)

    I realize that the cables outside the cabinets can also radiate noise but it would seem to me isolating the main sources of the noise from the logic level items would greatly reduce the possibilities of EMI problems.

    I would love to hear thoughts on this idea?

    Chris D.



  9. #9
    Member
    Join Date
    Jan 2005
    Location
    USA
    Posts
    12074
    Downloads
    0
    Uploads
    0

    Default Re: Electrical noise issues AGAIN - External Estop requested...

    Quote Originally Posted by Chris D View Post
    Related questions..

    Years back on industrial CNC machines, I recall that they used to keep most of the high powered transformers and power supplies in a separate cabinet from the logic level components. I can't recall if they put the servo drives there too though.

    Being that it is often a fight to get rid of or fix the problems with EMI on these DIY CNC machines, especially those using 5v logic levels, I am wondering if it would be beneficial to place the electronics in two separate cabinets.

    Cabinet #1 :
    Mains input
    Stepper power supply
    Logic power supply (and any others)
    Stepper (servo) drivers
    VFD for the spindle
    Any other high voltage / high frequency devices.

    Cabinet #2:
    PC (If placed in cabinet)
    CNC Controller board (Such as smooth stepper)
    Breakout board
    All logic level connections (limit switches, buttons, sensors, etc.)

    I realize that the cables outside the cabinets can also radiate noise but it would seem to me isolating the main sources of the noise from the logic level items would greatly reduce the possibilities of EMI problems.

    I would love to hear thoughts on this idea?

    Chris D.
    It is never a fight if your system is wired correctly

    Would make very little difference using ( 2 ) separate Boxes, and could make it worse in some cases, correct Grounding and wiring eliminates most problems , EMI travels in all power cables / wires, no matter what the voltage

    It appears that you have the Power Filter mounted on top of a Power supply if this is the case, this would not be acceptable, even though it was most likely doing it's job, it should be mounted on the Ground plane as close as possible to the VFD Drives input Power connections, your SMPS also may need there own Power filter on there input power lines

    Mactec54


  10. #10
    Community Moderator Al_The_Man's Avatar
    Join Date
    Dec 2003
    Location
    Canada
    Posts
    23634
    Downloads
    0
    Uploads
    0

    Default Re: Electrical noise issues AGAIN - External Estop requested...

    I have been building my own cabinets as well as retro-fitting others, and mainly used the same enclosure for all, it is customary to keep the power and heat producing devices towards the top are of the enclosure.
    If you have the luxury of doing it, it cannot hurt to keep separate if possible.
    Al.

    CNC, Mechatronics Integration and Custom Machine Design

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


  11. #11
    Member Chris D's Avatar
    Join Date
    Apr 2005
    Location
    USA
    Posts
    510
    Downloads
    0
    Uploads
    0

    Default Re: Electrical noise issues AGAIN - External Estop requested...

    Quote Originally Posted by mactec54 View Post
    It is never a fight if your system is wired correctly

    Would make very little difference using ( 2 ) separate Boxes, and could make it worse in some cases, correct Grounding and wiring eliminates most problems , EMI travels in all power cables / wires, no matter what the voltage

    It appears that you have the Power Filter mounted on top of a Power supply if this is the case, this would not be acceptable, even though it was most likely doing it's job, it should be mounted on the Ground plane as close as possible to the VFD Drives input Power connections, your SMPS also may need there own Power filter on there input power lines
    The trick is, knowing how to wire it correctly in the first place. Most hobbiest do this once or twice in a lifetime so mistakes are almost certain.
    The power filter is mounted in the only place I had left for it to fit. It was not part of the original design / layout and had to be added because of noise issues after it was put together. However, it is only about 4 inches of wire length away from the VFD and 12 inches away from the ground bar. In other words, it ain't gonna get any better based on what I have.

    As for the other power supplies, they very well could need filters but if they do, I will have to redo the entire cabinet which is part of the reason I was thinking I would use two cabinets instead of one.

    I do have an update on this issue but will post that in its own reply.

    Chris



  12. #12
    Member Chris D's Avatar
    Join Date
    Apr 2005
    Location
    USA
    Posts
    510
    Downloads
    0
    Uploads
    0

    Default Re: Electrical noise issues AGAIN - External Estop requested...

    Quote Originally Posted by Al_The_Man View Post
    I have been building my own cabinets as well as retro-fitting others, and mainly used the same enclosure for all, it is customary to keep the power and heat producing devices towards the top are of the enclosure.
    If you have the luxury of doing it, it cannot hurt to keep separate if possible.
    Al.
    Of course I had to do the opposite in my design :-) My stepper drives and VFD are at the bottom directly above the fans. The power supplies are also near the bottom. The good news is that nothing runs at "max" current and the cabinet barely ever feels warm to the touch nor do any of the components.

    So you think it could be a good idea to put the high power equipment in a separate enclosure? I am still trying to determine what to do next but have learned a bit more about the problem that I will post in a separate reply.



  13. #13
    Community Moderator Al_The_Man's Avatar
    Join Date
    Dec 2003
    Location
    Canada
    Posts
    23634
    Downloads
    0
    Uploads
    0

    Default Re: Electrical noise issues AGAIN - External Estop requested...

    I have always used the same enclosure with no problems.
    BTW, SMPS P.S.'s should not really need filtering due to the natural filter of the electronics, and they also generally have some filtering built-in anyway.
    Al.

    CNC, Mechatronics Integration and Custom Machine Design

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


  14. #14
    Member Chris D's Avatar
    Join Date
    Apr 2005
    Location
    USA
    Posts
    510
    Downloads
    0
    Uploads
    0

    Default Re: Electrical noise issues AGAIN - External Estop requested...

    UPDATE,

    I spent a lot of time checking to make sure everything that should be grounded is and that it goes back to the electrical supply conduit (along with the third prong). Using a VOM, I checked resistance between the cabinet and the machine frame and it is .3 ohms. I checked the shields to make sure they were all connected (which are on the limit switch cables and the spindle motor cables, etc.). They too are showing nearly zero resistance to the machine frame.

    With the problem still happening I started the process of elimination and started removing one element at a time that I recently added. To help with visual reference, I used my pocket scope to monitor noise on various connections to see if the noise changed with the removal of anything. Didn't find anything solid in the early tests but did find a problem with one cable.

    I have a USB to serial converter cable between a micro controller (which I just added) and the laptop which runs the machine. I put the scope on the TX line of that cable at the junction by the micro and that turned out to be very revealing. At that point, I could easily see the noise levels (max V of up to 2 volts) when the spindle was running and only about 20 to 40 mV when not running. I had some clamshell ferrites and started adding them and it made a BIG difference in the intensity of the noise peaks. With 3 of those on the USB cable near the TTL Serial end dropped the peak V down to a range of 50mV to a high of 600mV. With the ferrite cores on the cable the problem also stopped occurring.

    There was an interesting side step in that process too that was interesting. Windows had changed the Com port number of the usb-serial cable during one of my plug/unplug attempts. At that time the noise as I measured with the scope was worse. Once I reconfigured MACH 3 to use that com port, the noise levels dropped.

    Being curious, I then used the scope to check a lot more places to see where there was noise and not noise. I found noise even between the Cabinet ground and the machine ground points - saw nothing at all with the Fluke VOM. After a while of seeing all the noise everywhere, I gave up investigating further. I wasn't sure if what I was finding meant anything or not and second to that, had no idea how to make it go away. At this point it is like information overload for me.

    Tomorrow I am going to do some more monitoring with the spindle running and see if I get any faults.

    Damn this **** is fun!

    Chris D.



  15. #15
    Member
    Join Date
    Jan 2005
    Location
    USA
    Posts
    12074
    Downloads
    0
    Uploads
    0

    Default Re: Electrical noise issues AGAIN - External Estop requested...

    Quote Originally Posted by Chris D View Post
    UPDATE,

    I spent a lot of time checking to make sure everything that should be grounded is and that it goes back to the electrical supply conduit (along with the third prong). Using a VOM, I checked resistance between the cabinet and the machine frame and it is .3 ohms. I checked the shields to make sure they were all connected (which are on the limit switch cables and the spindle motor cables, etc.). They too are showing nearly zero resistance to the machine frame.

    With the problem still happening I started the process of elimination and started removing one element at a time that I recently added. To help with visual reference, I used my pocket scope to monitor noise on various connections to see if the noise changed with the removal of anything. Didn't find anything solid in the early tests but did find a problem with one cable.

    I have a USB to serial converter cable between a micro controller (which I just added) and the laptop which runs the machine. I put the scope on the TX line of that cable at the junction by the micro and that turned out to be very revealing. At that point, I could easily see the noise levels (max V of up to 2 volts) when the spindle was running and only about 20 to 40 mV when not running. I had some clamshell ferrites and started adding them and it made a BIG difference in the intensity of the noise peaks. With 3 of those on the USB cable near the TTL Serial end dropped the peak V down to a range of 50mV to a high of 600mV. With the ferrite cores on the cable the problem also stopped occurring.

    There was an interesting side step in that process too that was interesting. Windows had changed the Com port number of the usb-serial cable during one of my plug/unplug attempts. At that time the noise as I measured with the scope was worse. Once I reconfigured MACH 3 to use that com port, the noise levels dropped.

    Being curious, I then used the scope to check a lot more places to see where there was noise and not noise. I found noise even between the Cabinet ground and the machine ground points - saw nothing at all with the Fluke VOM. After a while of seeing all the noise everywhere, I gave up investigating further. I wasn't sure if what I was finding meant anything or not and second to that, had no idea how to make it go away. At this point it is like information overload for me.

    Tomorrow I am going to do some more monitoring with the spindle running and see if I get any faults.

    Damn this **** is fun!

    Chris D.
    You never mentioned in your first post the you had add a USB Etc. connections, they are prone to noise problems and usually needs a shielded cable with ferrites, it's even more fun when you don't have any problems like this

    As for the Power Filter how would you make it better by mounting it on and L shaped aluminum bracket that mounted to the Ground Plane not the power supply you have plenty of opinions on how to mount it

    Mactec54


  16. #16
    Member
    Join Date
    Jan 2005
    Location
    USA
    Posts
    12074
    Downloads
    0
    Uploads
    0

    Default Re: Electrical noise issues AGAIN - External Estop requested...

    Quote Originally Posted by Al_The_Man View Post
    BTW, SMPS P.S.'s should not really need filtering due to the natural filter of the electronics, and they also generally have some filtering built-in anyway.
    Al.
    Some of the cheaper SMPS put out lots of noise, the cheaper one's have no filters and need a Power Supply line Filter

    Mactec54


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

Electrical noise issues AGAIN - External Estop requested...

Electrical noise issues AGAIN - External Estop requested...

Electrical noise issues AGAIN - External Estop requested...