A system and method are provided for protecting a power grid against electric faults. A first circuit breaker is associated with a first electronic unit and positioned at a first hierarchy level. One or more additional circuit breakers, each including a corresponding second electronic unit, are positioned at one or more additional levels hierarchically lower than the first level and cascaded to each other. The first circuit breaker includes at least one semiconductor electronic breaking device. The first electronic unit is configured to, upon the appearance of an electric fault in a grid area, drive the breaking device to limit the current flowing through it for a predetermined period of time, and send to the circuit breakers on lower hierarchy levels an intervention command to allow intervention, among the circuit breakers that detected the fault, of the closest circuit breaker positioned immediately upstream from the area where the fault occurred.