GROUNDING SYSTEM AND PROTECTIVE SYSTEM FOR INCOMING AND DISTRIBUTING FACILITY

摘要

PROBLEM TO BE SOLVED: To provide a grounding system and a protective system which make ground switching of generators unnecessary and surely protect the generators. SOLUTION: From main common bus lines BUS-A, BUS-B, neutral points are grounded with low impedance, via grounding transformers ET1, ET2. Neutral points of generators G1-G4 are grounded directly with high resistance by transformers NT1-NT4. When ground fault is caused in main transformers MT1, MT2, ground fault overcurrent relays 51G1, 51G2 cut off only the fault transformer from the bus lines. Ground directional relays 67G1, 67G2 are made possible to generate a ground fault alarm to each feeder of the ground transformers. Ground directional relays 67G3-67G6 cut off each generator, in which ground fault is caused from the bus lines.