Coordination Study

[amps88]

I'm trying to gather information for a coordination study but am unsure what the X/R ratio pretains to for the primary, source transformer, or the secodary side.

 

[kingpb]

Given the impedance Z for the transformer, the X/R ratio of the transformer allows you to calculate the R and X components. Given the short circuit MVA of the system, allows you to calculate current and impedance of the system. The X/R ratio for the system also allows you to calculate the R and X components.

If this is causing you trouble, I would have to recommend that you consult with an engineer experienced in short circuit analysis.

 

[jtester]

The X/R ratio also is an indication of the asymmetry of the fault current. A large X will give a much higher inrush during the first cycles of the fault than a lower X.

Jim T