How does the parameter c-factor in the external grid for the complete method impact the results of a short circuit calculation


The parameter "c-factor" in the "Complete Short-Circuit"-page of an External Grid defines, under which correction factor the given values for short circuit power Sk'' and current Ik'' were determined.


The short circuit power of the external grid is typically provided by the network operator for the connection point, where the External Grid element represents the network operators grid. The provided values are typically calculated using a network calculation software and might consider a voltage correction factor. Since the complete method neglects those voltage correction factors, the mentioned c-factor defines under which circumstances the given short circuit values were determined. Using this parameter, the short circuit power under normal operating conditions (as determined in the load flow intialisation) is calculated to get more realistic values.

If a short circuit at the external grids terminal according to the complete method should result in the values for Sk'' and Ik'', the c-factor should be set to 1.0. The resulting difference may be caused by the load flow initialisation. To fit them exactly, in the short circuit command the load flow initialisation has to be deactivated, the user defined c-factor should be set to 1.0 and all of the positive sequence data has to be ignored (Advanced Options page in the short circuit calculation command dialog).