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Frankie
Frankie asked in Science & MathematicsEngineering · 9 years ago

Electrical help transformer help?

A transformer has a 120volt primary rated at 3amps. The secondary winding is rated at 18amps. The secondary voltage rating has how much volts?

3 Answers

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  • whycantigetagoodnickname
    Lv 7
    9 years ago
    Favorite Answer

    In an ideal transformer (ignoring reactances and other electrical losses)

    Volts x Current in = Volts x Current out (that is power in = power out)

    So

    120 x 3 = Volts x 18

    360 = 18 Volts

    Volts = 20

  • Rick
    Lv 7
    9 years ago

    The turn ratio is 18/3=6. Therefore the secondary voltage is 120/6=20.

  • billrussell42
    Lv 7
    9 years ago

    With no losses in the transformer, the power in the input (120 x 3) equals the power in the output.

    120 x 3 = V x 18

    V = 120/9 volts

    But current ratings are set by a number of factors such as wire size. That means they may not equal the actual current.

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