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Finding efficiency between transformers.

  1. Mar 4, 2012 #1
    Ok, I have a primary and secondary coil. I set up a transformer between them. Each has 400 turns of coil(N). The primary coil produces a potential difference of 2.988 V. The secondary coil has a potential difference of 0.0551 V.

    For the efficiency, I used the equation (Np*Vs)/(Ns*Vp) * 100%

    Np-turns of primary coil(400)
    Vs- potential difference of secondary coil(0.0551)
    Ns- turns of secondary coil(400)
    Vp-potential difference of primary coil(2.988)

    When I plug them in, I get 1.84% efficiency.

    Am I messing the formula up, plugging in the wrong values. etc?
    1.84% seems awfully low.
    Thanks.
     
  2. jcsd
  3. Mar 4, 2012 #2

    Redbelly98

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    For equal number of turns on the primary and secondary, a 100% efficient transformer would have equal voltages on the primary and secondary. But the problem statement does give an awfully low value for the secondary voltage, namely 1.84% of the primary voltage.

    Perhaps if you can you post the question in its exact wording, I can see if there is something we are missing.
     
  4. Mar 4, 2012 #3
    This was a lab experiment, and these values were measured or given. the two coils were set up with an iron core and were faced toward eachother with 2 voltage probes acting as a voltmeter.

    Later on for a separate trial, we had the iron core placed right through the transformer with still two 400 coils, and then I calculated a reasonable 60.4% efficiency using the same formula as earlier.

    I'm guessing that its a possibility that the more O-shaped iron core involved, the more efficient the transformer was, and that having no O-shaped iron core made it extremely, yet unbelievably, inefficient.
     
  5. Mar 5, 2012 #4

    Redbelly98

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    Okay, it makes more sense now. Without the iron core in place, the coils are not coupled as strongly to one another.
     
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