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X/R Ratios

X/R Ratios

X/R Ratios

(OP)
What is the X/R ratio.  If you are given the %impedance and the X/R ratio can you find the total impendance.  Is the % imepedance given the reactive portion, then do you use the x/r ratio to get the real portion.

RE: X/R Ratios

The %impedance is dependant on the impedance. Use the % impedance to calculate the actual impedance. Use the quadratic equation to determine the X and R from the impedance and the ratio.

Is this a homework question?
yours

RE: X/R Ratios

z^2 = x^2 + r^2


Mike

RE: X/R Ratios

Hi mpparent
Did I mean the law of cosins instead of the quadratic equation. Sorry if I caused any confusion.
yours

RE: X/R Ratios

i) What is the X/R ratio: This ration could provide us more than a simple mathematical quotient of the system reactance over the system resistance. X/R ratio will provide us with the characteristic of the short circuit in term of the following:
a)    Rate of decay of the dc component.
b)    Degree of asymmetric
c)    Interrupting capability rating of protective devices.

ii) If you are given the % impedance and the X/R ratio can you find the total impedance.  No. To obtain actual values of X and R, the total impedance is needed in actual values not in percent.  The best that you could get is the %X and %R as follow.
                                   X/R = tag(q) ==>        q=atan(X/R)
                                   %X = %Z.sin(q) & %R=%Z.cos(q).

iii) Is the percentage impedance given the reactive portion, then do you use the x/r ratio to get the real portion. Appears that you are confusing impedance with reactance. The following relation should be considered.
        %Z = %R + j.%X      Where: j = (-1)^1/2
      |%Z| = (%R^2+%X^2)^1/2

The between the impedance and reactance percent of impedance

RE: X/R Ratios

Thanks cuky2000
respectfully

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