Short-Circuit Ratio¶
SCR. The ratio between short circuit apparent power from a 3LG fault at a given location in the power system to the rating of the location.
Definition by NERC¶
Source: 1 (p1)
SCR is defined as the ratio between short circuit apparent power (SCMVA) from a 3LG fault at a given location in the power system to the rating of the inverter-based resource connected to that location. Since the numerator of the SCR metric is dependent on the specific measurement location, this location is usually stated along with the SCR number.
\(SCR_{POI} = \frac{SCMVA_{POI}}{MW_{VER}}\)
Where \(SCMVA_{POI}\) is the short circuit MVA level at the POI without the current contribution of the inverter-based resource, and \(MW_{VER}\) is the nominal power rating of the inverter-based resource being connected at the POI.
Last modified: 2025-11-29
Related: grid-strength · stability · weighted-short-circuit-ratio · composite-short-circuit-ratio · short-circuit-ratio-with-interaction-factors · generalized-short-circuit-ratio
← Severity Risk Index · Short-Circuit Ratio with Interaction Factors →
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NERC (2017). Integrating Inverter-Based Resources into Low Short Circuit Strength Systems. https://www.nerc.com/globalassets/who-we-are/standing-committees/rstc/irpwg/item_4a.integrating-_inverter-based_resources_into_low_short_circuit_strength_systems-_2017-11-08-final.pdf ↩