This Selection Guide covers some of the basic considerations used when selecting relays for the protection of Medium Voltage Power Systems. It is organized by protection packages according to the types of equipment generally encountered in medium voltage systems: Generators, Motors, Feeders, Transformers, Buses, and Incoming Lines.
Packages are based on commonly used power system configurations. Other considerations may be needed if unique power system arrangements are used.
Automatic Reclosing
Differential Protection
Phase-Overcurrent Protection
Ground-Overcurrent Protection
High Impedance Ground Fault Detection
Directional Phase-Overcurrent Protection
Directional Ground-Overcurrent Protection
Open-Phase Protection (Negative-Sequence Voltage)
Directional Power, Under-Frequency, & Under-Voltage Protection
