Under what condition is a Manual Load Dump Warning issued?

A Manual Load Dump Warning is issued when an Interconnection Reliability Operating Limit (IROL) has been violated for a specific duration, which is typically five minutes. This warning indicates that the situation has escalated to a point where manual intervention may be necessary to ensure the reliability of the electric grid. By issuing this warning, operators are alerted to the critical status of the system and can take appropriate measures to mitigate the risk of further issues, such as potential blackouts or system failures.

In contrast, the other options pertain to specific actions or conditions that do not directly relate to the violation of IROL as a trigger for issuing a Manual Load Dump Warning. For instance, emergency load management activation, voltage reduction actions, and insufficient primary reserves do indicate critical conditions or actions within the transmission system but do not specify the systematic criteria that warrant the particular Manual Load Dump Warning that arises from an IROL violation.