Electromagnetic Interference

Discussion in 'General Electronics Chat' started by Boomer999, Jun 11, 2016.

  1. Boomer999

    Thread Starter New Member

    May 2, 2013
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    Hi guys. Trying to solve a problem, and I am hoping some one on here can help me. My friend has a 3 phase milling machine and lathe in his shop. And one either one is in use, he cant use the wireless(not a cell phone) phone in his shop. I am guessing the motors are creating Electromagnetic interference. Is that correct? Or is it something else? If it is the motors creating EMI is there something that can be done to fix it?

    Thanks for your help
    Boomer
     
  2. dl324

    Distinguished Member

    Mar 30, 2015
    3,250
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    What frequency is the wireless phone? Has he tried phones using different frequencies?
     
  3. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,804
    1,105
    Identifying the route the interference takes (conduction/radiation) could be helpful.
    Is the phone base station powered from the same circuit that supplies the motors?
    Does the phone work correctly if used in a different room while the motors are running?
     
  4. Boomer999

    Thread Starter New Member

    May 2, 2013
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    He has tried changing frequencies. All that were available to him. Thank you for your input
     
  5. Boomer999

    Thread Starter New Member

    May 2, 2013
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    The phone is 11o volts, so no its on a different circuit. I will have to ask him if it works in the office area. Thank you for your response.
     
  6. Marley

    Member

    Apr 4, 2016
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    Do the motors in the machines use variable speed drives (VFDs or inverters) to control motor speeds? 3-phase motors don't normally create EM interference except when starting or stopping.

    Does the workshop have a 3-phase supply or is there a converter?
     
  7. Boomer999

    Thread Starter New Member

    May 2, 2013
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    it is a 3 phase supply. power comes into a splitter box, 3 phases go out to the 3 phase panel, and then there is a single phase panel off of the splitter as well. There are no vfd on either machine. Both machines use gear boxes to adjust the speed.
    Thank you for your response
     
  8. Boomer999

    Thread Starter New Member

    May 2, 2013
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    The phone is in the office area. And it does not work in the back of the shop or the office area when either piece of equipment is being used.
     
  9. Marley

    Member

    Apr 4, 2016
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    Hard to say what the cause is.

    What happens if you use an AM or FM radio while the machines are working?
    Try both wavebands. Tune to a fairly weak station when the machines are off. Then switch the machines on. Are the stations affected?

    Are the machines properly earthed (grounded)?
     
  10. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    If the phone base station and the motors don't use a star (single-point) ground system then motor current could be causing voltage shifts on the base station's ground line.
     
  11. Techno Tronix

    Member

    Jan 10, 2015
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    What is the frequency? You can change the existing frequency and try it again.
     
  12. BR-549

    Well-Known Member

    Sep 22, 2013
    2,004
    394
    Boomer,
    You wouldn't happen to have a SDR radio dongle, that you could plug into the office computer, do you?
    You can get one on ebay from a regional (quick) supplier for 10 - 15 bucks. 20 bucks for a high quality one.
    Mine tunes, scans and displays 60 MHz to 1.2 GHz.
    Extremely handy instrument for $20.
    Not to mention what a great radio it is.
     
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