Differential Relay: Compares currents at two points; operates when there is a difference (used in transformers and generators). They are intended to quickly identify a fault and isolate it so the balance of the system continue to run under normal conditions. The selection and applications of. This handbook covers the code of practice in protection circuitry including standard lead and device numbers, mode of connections at terminal strips, colour codes in multicore cables, dos and donts in execution. Types of Protective Relays: Protective relays are categorized by their mechanism (electromagnetic, static, mechanical) and function. Relion protection and control relays for several application reduce complexity. 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. The Art and Science of Protective relaying I N D E X1 Abnormal conditions other than short circuits,, 8 A-c tripping, 335 Angle-impedance relay, 79 for tripping on 1088 of synchronism, 362 Angle of maximum torque, adjustment,, 57 of power relays, 52, 55 of shortcircuit relays, 55 Arcs, effect on. What it is: Think of relay coordination as the “brain” of the power grid—it's the art of making sure that when a fault happens (like a tree falling on a wire), only the local area loses power while the rest of the city stays bright. The Goal: We use 7 core principles to protect people, save.