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The terminal voltage of a Y-connected load consisting of three equal impedances of 17.3205+j10 ohms is 4.4kV line-to-line. The impedance in each of the three lines connecting the load to a bus at a substation is Z[L] = 0.362+j1.35. Find the line-to-line voltage at the substation bus.

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  • 1 decade ago
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    i'll just give you the method how to solve this kind of problem because it's been more than 35 yrs ago, that i've been solving this in my higher EE class.

    first step is convert your rectangular form into polar form, compute only the one phase to neutral, anyway you have a balanced load.

    divide your line to line voltage at the load side by square root of three to get the voltage line to neutral, that is 4.4/1.732.

    the polar form of 17.3205+j10 will give you the impedance.

    compute for the line current, I line= Vn/Z, this I line passes thru

    Z(L)= 0.362+j1.35(compute polar form to get Z(L), you can now compute for the voltage drop on your line by the formula

    V drop= I(L)* Z(L),

    Total V/phase to neutral= V drop+ 4.4/1.732

    now compute for line to line voltage:

    V line to line at the substation bus= square root of 3*( Vdrop+4.4/1.732)

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