Topic on Talk:Generator protection

How can the equation for x"d have x"d in on both sides of the equation?

NVM. I see the difference between X"d and x"d.

Hi @DMullins in fact on the right of the equation you have $x_{d}^{''}$ , expressed in %, which is a characteristic of the generator during subtransient phase (= subtransient reactance, expressed in %, only the reactance is used because the resistance is negligible). This characteristic is provided by the manufacturer (see Fig.N5 for an example of manufacturer impedance table in %). It is used in the equation to calculate $X_{d}^{''}$ , which is the generator actual short-circuit impedance (in ohms) during subtransient phase. Does that clarify it?

I also made small modifications to this paragraph (fine-tuned the look&feel of the equation, used an inline equation for $x_{d}^{''}$ for coherence, I hope it helps making things more clear