2.

A transmission system shall be in the alert state when: voltage and power flows are within the operational security limits defined in accordance with Article 25; and the TSO's reserve capacity is reduced by more than 20 % for longer than 30 minutes and there are no means to compensate for that reduction in real-time system operation; or frequency meets the following criteria: the absolute value of the steady state system frequency deviation is not larger than the maximum steady state frequency deviation; and the absolute value of the steady state system frequency deviation has continuously exceeded 50 % of the maximum steady state frequency deviation for a time period longer than the alert state trigger time or the standard frequency range for a time period longer than time to restore frequency; or at least one contingency from the contingency list defined in accordance with Article 33 leads to a violation of the TSO's operational security limits, even after the activation of remedial actions.

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Source: EUR-Lex (Cellar) · retrieved 2026-11-04 · Text as adopted (Official Journal); later amendments are not incorporated in this text.