Protection against Ground-Faults in Tetrapole Unit-Generator with Two Parallel Branches in Phase

Operating conditions of the 100% ground-fault protection of the generator stator winding based on the 3rd harmonic voltages depends on parameters of ground-fault circuit. The breakdown channel in place of damage of main isolation of stator windings is the most essential and most complicated element of ground-fault circuit during ground fault in stator windings. Its proprieties, especially resistance, decide about regularities of operating conditions of ground-fault protections. In this paper the influence of value resistance of breakdown channel on operating conditions of the ground-fault protection are presented. Analysis was done for tetra pole unit-generator with two parallel branches in phase of stator winding. In paper results of simulation of operating conditions ground-fault protection at different values resistance of breakdown channel are shown.