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Answers Please. Electrical Technology.

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1. A load of 2.5kW takes a current of 12 Amp from a 230 Volt supply. Calculate the power factor.


2. Three single phase loads are to be connected to a three phase supply. All at unity power factor. The loads are,


i, 60 Amp.


ii, 50 Amp.


iii, 40 Amp.


By any method determine the neutral current.


Z.
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  • 0
    My method:


    In = I1+ I2 + I3 where all terms are phasor quantities


    In polar form


    60 @ 0 degrees + 50 @ 120 degrees + 40 @ 240 degrees


    In rectangular form (you can obtain this using the Polar to Rectangular function on a calculator or trigonometry)


    by calculator function


    I1 = 60 + j0

    I2 = -25 + j43.3

    I3 = -20 - j34.64


    collecting terms

    Re    Img

    60    0

    -25    43.3

    -20    -34.64


    15  + j8.66


    in polar form (by calculator)


    17.32A @ 30 degrees


    Which by the way proves that I got my angle wrong in my earlier post.


    Regards

    Geoff Blackwell
Reply
  • 0
    My method:


    In = I1+ I2 + I3 where all terms are phasor quantities


    In polar form


    60 @ 0 degrees + 50 @ 120 degrees + 40 @ 240 degrees


    In rectangular form (you can obtain this using the Polar to Rectangular function on a calculator or trigonometry)


    by calculator function


    I1 = 60 + j0

    I2 = -25 + j43.3

    I3 = -20 - j34.64


    collecting terms

    Re    Img

    60    0

    -25    43.3

    -20    -34.64


    15  + j8.66


    in polar form (by calculator)


    17.32A @ 30 degrees


    Which by the way proves that I got my angle wrong in my earlier post.


    Regards

    Geoff Blackwell
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