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Magnetic Fields

Power losses and high-voltage transmission

  • 3 things to know
  • Unit A2 2

Overview

Four main causes of power loss in a transformer, hysteresis loss and flux leakage and how is it reduced.

What you need to know

Answer each one before you reveal it.

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Key term

Name the four main causes of power loss in a transformer.

Key term

What causes the copper loss in a transformer and how is it reduced?

Key term

What causes eddy current loss in a transformer and how is it reduced?

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    Name the four main causes of power loss in a transformer.

    Model answer

    Resistance of the copper windings, eddy currents in the core, hysteresis in the core, and flux leakage between the coils.

  2. 2

    What causes the copper loss and how is it reduced?

    Model answer

    The resistance of the windings dissipates I²R as heat, and it is reduced by using thick low-resistance copper wire.

  3. 3

    What causes eddy current loss and how is it reduced?

    Model answer

    Currents induced in the core itself heat it, and the loss is reduced by laminating the core with insulated sheets so the current paths are broken.

  4. 4

    What is hysteresis loss?

    Model answer

    Energy dissipated in repeatedly magnetising and demagnetising the core as the current alternates.

  5. 5

    How is hysteresis loss reduced?

    Model answer

    By using a magnetically soft material such as soft iron, which is easily magnetised and demagnetised.

  6. 6

    What is flux leakage and how is it reduced?

    Model answer

    Flux from the primary that does not pass through the secondary, reduced by winding the two coils on the same limb of a closed core.

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