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Current transformer output

  1. Jan 21, 2010 #1
    i can't seem to understand why with current transformer if the primary winding is reconnectable the rated output stays the same. but rated output depends on turn ratio if the secondary winding is reconnectable??
    why??
     
    Last edited: Jan 21, 2010
  2. jcsd
  3. Jan 21, 2010 #2
    I don't really understand your question, but here is what I know about current transformers.

    For monitoring ac currents, the primary is usually a single turn through a toroid. The N-turn secondary, if shorted or terminated in a resistive load, will have 1/N times the primary current. Shorting the secondary does no damage to the transformer. The current in the secondary opposes the primary current, and prevents the toroid magnetic core from going into saturation (too high a dB/dt). There is usually a maximum volt-seconds limit on the output.

    For monitoring dc currents, the toroid has to have low permeability to prevent core saturation (Bmax > 1 Tesla) at maximum primary current. To monitor the dc current, the voltage output (into a high impedance termination) should be integrated in a good low-leakage op-amp integrator wilth a low-leakage capacitor in the feedback loop. See voltage integrator design in
    http://www.matthewmassey.com/RogowskiCoil/ [Broken]
    Bob S
     
    Last edited by a moderator: May 4, 2017
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