To serve for exprimental assignment, doing research on crience, especially to create special branch power system. The university has equiped for electricity energy lab a set distance protect EP3 - 1636 - M, this set consecrate to protect the distance for the line that belong to power network of high pressure and super-high pressure. Set protect has applied many new progressive science, especially in using transistorized equipmend under the interated circuit form (IC) to replace for electromechanis relays. After researching, the author introduce to you one of applications that is the usage of the interated circuit called K553 - YD2 in set EP3 - 1636 - M to replace electromagnectic relay in oder to distance protection in Power system, to serve the teaching and conducting experiments on the protection of this distance.