Power grid

N-1 security

The “n-1 criterion” is an important factor in ensuring secure operation of the transmission grid. Adhering to the n-1 criterion ensures that the elements remaining in operation after occurrence of a contingency (failure of a line, transformer, etc.) are capable of accommodating the new operational situation without violating operational security limits, thus avoiding subsequent failures and minimising the risk of widespread service interruptions. In the Austrian transmission grid, (n-1) security is recalculated every five minutes so as to maintain overall operation of the power grid in the event that equipment should fail or malfunction.