Patent ID: 8736090

Claim:
A protection arrangement of an electric power system, the electric system comprising a generator set, the protection arrangement comprising a relay arrangement for measuring current, voltage or both of an electric grid, which relay arrangement is adapted to detect over-current, under-voltage or both, the generator set being separable from a grid when over-current, under-voltage or both are detected, and the detected over-current, under-voltage, or both does not stop before a critical clearing time, the critical clearing time determining a period, during which resynchronization of the generator set with the grid is possible, wherein the protection arrangement comprises a speed/load controller that is in connection with the relay arrangement, which speed/load controller is arranged to drive a prime mover of the generator set as a response for said detection, said speed/load controller being connectable with said prime mover, the speed/load controller driving power output of the prime mover to a lower level when over-current, under voltage or both is detected, the driving of the power output to the lower level is arranged to initiate during a fault of the power system and before the critical clearing time of a generator of the generator set.