How do you get %Z

[Murloc]

seems that transformer are given a certain Z% usually that is given by the utility company,.
I need to get the Z% of some conductors in order to do a calculation.

given
X
R

Z = sqrt(X^2 +R^2)
Z% = sqrt(X%^2 + R%^2)

Solve for
Z%, X%, R% - can't seem to find a formula for any of these

--

 

[dkidd]

Θ = Arctan X/R
X = Sin θ * Z
R = Cos θ * Z or X / (X/R)



Transformer R and X
%Z = 5.75 and X/R = 7
Inverse Tangent 7.00 = 81.8699°
X = Sin 81.8699* 5.75 % = 0.9899 * 5.75 % = 5.6919%
R = Cos 81.8699* 5.75 % = 0.1414 * 5.75 % = 0.8131%

The Importance of the X/R Ratio in Short Circuit Calculations​

The X/R ratio can affect how two impedances are added together. The X/R defines the impedance angle and should be considered for short circuit calculations
brainfiller.com

 

[ron]

The transformer impedance comes from the supplier, whether the utility or the manufacturer. For the conductors, you can get it from several resources. Eaton Bussmann has a nice booklet for a particular point to point calculation method if you are doing it by hand.

https://www.eaton.com/content/dam/eaton/products/electrical-circuit-protection/fuses/technical-literature/bus-ele-an-3015-electrical-plan-review.pdf