The power industry has experienced swift changes over the last few years; the most obvious is the move towards larger number of smaller decentralized power sources, which impose higher demand on the grid stability. As result, the network operator requirements on functionality and performance of protection devices become more demanding and are still increasing.
To avoid any dangerous situation, like the vast rolling black-out that happened in the US in 2003, generator operators are lately requested to embed protection against pole slip and so prevent the grid from island non-synchronous operation.