This paper analyzes the basic principle and function of relay protection, summarizes the common fault types, and analyzes the fault analysis methods and treatment measures combined with actual cases. Relay protection plays a crucial role in ensuring the safe and reliable operation of electrical power network transmission and distribution systems. Of the four main characteristics of a good protection system (i. ) Selectivity, Stability, Speed and Sensitivity, the first and foremost is Selectivity. It implies that in the case of a fault in the network, only the protective device that is closest to the fault shall respond first and should. Long term cost reduction (TCO) for trainings and maintenance by reduce variety of relays A fast and selective arc fault mitigation for air-insulated LV & MV switchgear and Relion protection and control relays and sensor technology protect staff and plant facilities for many years. Recognized under 2(f) and 12 (B) of UGC ACT 1956 (Affiliated to JNTUH, Hyderabad, Approved by AICTE - Accredited by NBA & NAAC – 'A' Grade - ISO 9001:2015 Certified) Maisammaguda, Dhulapally (Post Via. Kompally), Secunderabad – 500100, Telangana State, India To introduce all kinds of circuit.