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Best Grounding Scheme For Pwm Electromagnet, Pwm electromagnet digital/analog signals

Discussion in 'General Electronics Discussion' started by fernandomierhicks, Aug 20, 2012.

  1. fernandomierhicks

    fernandomierhicks

    4
    0
    Mar 5, 2012
    Hi:

    I have a setup were I run a electromagnet with a PWM signal using 20 volts, usually at low dutycyles < 20%. PWM frequency in the low kHz range.

    Around this electromagnet I have various sensors, cirucits etc.All of this (electromagnet and circuits) is inside a metal chamber (faraday Cage). I need to run some signals outside this chamber, analogue and digital.

    The power supplies for the Electromagnet and the other circuitry are ground-isolated.

    I want to reduce the noise that the Electromagnet is going to produce on my signals both because of the pulsing and the EM interference.

    I was thinking of using coaxial cables for all my signals, using a star scheme once the wires are inside the chamber, so I will have a dedicated ground wire.

    Should I also use coaxial cable for the electromagnet leads? Should I ground the shield on this wire to my general "signal ground"?

    Should I ground both ends of my signal wires shield?, lets say to the frame?

    Any other suggestion recommendation is appreciated, wire types are flexible.

    Thanks

    Fernando
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,191
    2,692
    Jan 21, 2010
    If you use coaxial cable, I think the best bet is to connect the coax shield to the cage where it enters/exits.

    On the other hand, you *may* be able to get away with a simple twisted pair.

    If your signal level is reasonably high, and the impedance low, you will obviously have less problems than in the reverse case. Understanding the signals is key.
     
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