1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

EMI - induced current on two parallel wire

  1. Dec 8, 2008 #1
    I would like to quantify the EMI on a circuit and I am confused on how to do that. I have two parallel wires that are laying on top of each other. I have tried to calculate the flux linkage and came up with:

    [tex]\Lambda[/tex] = [l*[tex]\mu[/tex]o*I/(2pi)]*ln((d-a)/a)

    where a=radius of each wire, d=distance between the center of the wires, l=length of the wires, I=current on wire 1, and [tex]\mu[/tex]o*=permeability of free space.

    I don't understand how this would induce a current on wire 2 though.

    I'd really appreciate any help with this issue.

    Thanks,
    J
     
  2. jcsd
  3. Dec 8, 2008 #2
    A constant current will not induce a current in another wire; induced current is proportional to the change in the original current.
     
  4. Dec 9, 2008 #3
    Thank you for your reply. You are right. I'm sorry I forgot to indicate that the problem is occuring because inrush current. So, there would be a change in current. Do you know how to calculate the change in current on wire 2 due to a change in current on wire 1?
     
  5. Dec 9, 2008 #4

    Defennder

    User Avatar
    Homework Helper

    It depends on how exactly the current is changing. You don't necessarily need a change in current; a change in magnetic flux through some pre-defined surface or where magnetic flux lines are being cut suffices as well.
     
  6. Dec 9, 2008 #5
    If I could measure exactly how the current is changing on wire 1 do you know how I would be able to calculate the change in current on wire 2? Does the flux linkage equation apply here? If so, how does it translate into a change in current on wire 2?

    Thanks!
     
  7. Dec 9, 2008 #6

    Defennder

    User Avatar
    Homework Helper

    You have to use Faraday's law here:
    [tex]Emf = -\frac{d\Phi_B}{dt} [/tex].
    So this gives you the induced emf on wire 2. To get the induced current, divide emf by resistance of wire 2. That's all I can say if you don't provide any more information on the setup.
     
  8. Dec 9, 2008 #7

    berkeman

    User Avatar

    Staff: Mentor

    You can have both inductive and capacitive crosstalk. The capacitive crosstalk is just coupling from wire-to-wire. Inductive coupling requires tso loops to couple the energy. So don't ignore the return paths of the wires in your inductive crosstalk calculation.
     
  9. Dec 11, 2008 #8
    thanks for the responses.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: EMI - induced current on two parallel wire
  1. Current in a wire (Replies: 10)

Loading...