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Magnetical filed influence

Discussion in 'Electrical Engineering' started by 7, Jan 9, 2004.

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  1. 7

    7 Guest

    Some days ago I comment in this group a problem with a film recording
    system. Some of you comment various possibilities and we have found, we
    think a magnetical field influence in the system. The idea comes from
    "**THE-RFI-EMI-GUY**" (thanks a lot).

    We put the system far from the transformer and the images were perfect
    except one moment. We have checked that in that moment we connect the alarm
    in the office and this alarm goes by mobile telephone connection. May this
    phone call interference the system?.

    Thanks to all.

    Fernando
     
  2. SQLit

    SQLit Guest

    Could be a grounding issue as well. I had a customer a long time ago that
    wanted to move 700 feet of wiremold up 3 feet. I asked how he had figured it
    out. He turned on the monitor to his computer and it was wavey.. He put the
    monitor on a cart and moved to the end of the cables and it was fine...
    hence the 3 foot request. I did some research and found the neutrals and
    grounds were tied together in his local sub panel. ( supposed to be
    seperate ) Contractor did not realize that the local panel was one of 30 in
    the building and was not the service. All better and not much money spent.
     
  3. 7

    7 Guest

    Thanks for your response.

    We have checked our ground connection in all the building and looks good.

    We have put far the system from the transformer and also from the alarm and
    the test has been almost perfect. ( There was only one movement in one frame
    in 17 second of film, about 4 hours working the system. ) This movement is
    at the same time we went out the office, so we are trying to determinate
    what happened at that moment.

    Now we are trying to find mu metal to cover the system.

    Thanks to all,

    Fernando
     
  4. Glad I could help Fernando.

    Yes, an RF field from a mobile phone can affect the system just as the
    power system can.
    Your Mu metal fix is the way to go to fix what sounds like a very
    sensitive and complex environment.

    Joe
     
  5. Louis Bybee

    Louis Bybee Guest


    The company I work for was invited to attempt resolution for a computer room
    random interruption of service issue that a few other groups had failed to
    locate, or correct.

    It was a rather tense first meeting with much screaming, and finger
    pointing. Hardware people, software people, power company, and others all
    pointing towards any of the groups to shed attention away from themselves.

    After a period of bringing outside IT people to analyze software
    compatibility, detailed examination of the equipment and cabling in that
    portion of the building, in depth RF and magnetic field measurements, and
    monitoring for power quality issues, we detected intense magnetic fields
    coming from one wall as the only likely anomalies. As it turned out on the
    immediate other side of one wall was the main electrical room for the entire
    multi occupancy building. Multiple large transformers, and other electrical
    equipment right on the other side of the wall. After being advised of the
    cause of their issue, and refusing to relocate the computer room, extensive
    shielding was installed on both sides of the wall, and the problems ceased.

    You would think someone would have evaluated the intended computer room site
    a bit before spending that amount of money for it's construction. If they
    had paid for a study to locate it in the worst possible location I doubt
    another area would have triumphed! :-]

    Louis--
    *********************************************
    Remove the two fish in address to respond
     
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