How long is the limit for post-contingency thermal limits during a load dump?

The post-contingency thermal limits during a load dump are typically established to ensure the reliability and stability of the transmission system. In this context, a duration of 30 minutes is generally used to allow for transient conditions after a contingency event. This timeframe is critical because it offers a sufficient period to allow for the system to stabilize before load adjustments or re-dispatching of generation resources is needed.

Maintaining thermal limits for this duration helps to prevent overheating of equipment, avoids damage to transmission lines, and ensures that systems remain within operational standards to reduce the risk of outages or damage to the grid infrastructure. The 30-minute limit provides a balance between the immediate operational needs following a disturbance and the necessary time frame for reliable system performance while addressing the thermal characteristics of equipment and lines.