A design project to evaluate the protective device settings for an industrial plant

Results of an undergraduate student project to perform a short-circuit and coordination study for a major industrial plant are presented in the form of a tutorial. The plant was supplied by parallel 34.4 kV lines from the utility which was reduced to 4.16 kV and distributed to five, dual-fed substations within the plant. Expansion of the plant required the addition of a sixth substation, which could affect the suitability of protective devices, and their settings, throughout the plant. The authors explain the procedure used to conduct the study, and discuss some considerations when developing the plant one-line diagram, calculating the available short-circuit currents, and coordinating the settings of series protective devices