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EMC Probz I think ? - Help !!!!!

Discussion in 'General Electronics Discussion' started by Harleyworks, Dec 12, 2010.

  1. Harleyworks

    Harleyworks

    2
    0
    Dec 11, 2010
    Morning All,

    I currently have a project that controls a 1hp motor from a frequency inverter operating from filtered mains input. The inverter "agitates" the motors at 30Hz, 35Hz, 40Hz and 50Hz.
    With the inverter moved away from the motor assembly all works fine, however, when moved back into close proximity, all goes loopy, it seems to me that the pulses from the motors at start-up / operation are so heavy that they "knockout" the inverter function.
    The inverter is digital, and I have tried to re-programme start up, lead,lag stall ect, but as mentioned all is ok when the inverter is moved away.

    (the output from the inverter is directly wired to the motor assy, and a magnetic core assy is currently wrapped around the wire assy)

    Any ideas very greatly appreciated...........desperate !!!
    Many thanks to all
     
  2. davenn

    davenn Moderator

    13,289
    1,756
    Sep 5, 2009
    so is there a reason you cant keep the inverter at that ok distance from the motor ?
    it may be your only choice to stop the intereference

    Dave
     
  3. Harleyworks

    Harleyworks

    2
    0
    Dec 11, 2010
    no, no really as the unit was originally designed with the inverter in the "non-working" position, as its a commercial device, the practicallity of fitting outside the enclosure is a non starter, hence I need to find a solution to making functional in position, (I have noticed that with other units, they seem to function, very intermittant tho, so I assume that this may be somewhat border-line,
    Totally lost and have no idea how to resolve, I have shortened all associated cable assy and evenn wrapped the outers in silver foil, attempted to encase the inverter in foil tape too, any thoughts greatly appreciated at this point
     
  4. Resqueline

    Resqueline

    2,848
    1
    Jul 31, 2009
    Interferences are almost never easy to resolve.
    If the interference feedback is magnetic in nature then steel (+ maybe copper/aluminum) sheets between the motor and the controller might help.
    If RF goes to the motor (& then back somehow) then winding supply wires through a ferrite core might help. It seems you have tried this
    Careful consideration of the motor grounding layout might also lead to a solution. Capacitively coupled RF currents may take unexpected paths (frame/leads).
     
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