RFX, the largest machine for magnetic confinement of plasmas in the RFP line, is provided with a system named SGPR specifically designed for the machine global protection against fast faults which can develop in the plasma, in the windings, in the power supply circuits and in the control system. SGPR is a cabled logic HLL machine, able to organise in few tens of microseconds coordinated machine protection, dealing with more than forty fault signals and activating almost thirty protection commands. SGPR design, manufacture and test program conform the quality control criteria necessary to assure the required high reliability. After a careful and cumbersome commissioning work the system has assumed its protection role. Up to now it has been called to a number of interventions which, even if never due to major faults, have shown its capability of proper operation.