GE P24DM - Page 20

Figure 39: Directional angles 114
Figure 40: *Directional Earth Fault logic with negative sequence polarisation (single stage) 114
Figure 41: Current level (amps) at which transient faults are self-extinguishing 115
Figure 42: Earth fault in Petersen Coil earthed system 116
Figure 43: Distribution of currents during a Phase C fault 116
Figure 44: Phasors for a phase C earth fault in a Petersen Coil earthed system 117
Figure 45: Zero sequence network showing residual currents 117
Figure 46: Phase C earth fault in Petersen Coil earthed system: practical case with resistance
pr
esent
118
Figure 47: Fuse characteristic 120
Figure 48: Current distribution in an insulated system with C phase fault 121
Figure 49: Phasor diagrams for insulated system with C phase fault 122
Figure 50: Directional tripping characteristic 124
Figure 51: Current distribution in Petersen coil earthed system 125
Figure 52: Distribution of currents during a C phase to earth fault 126
Figure 53: Theoretical case - no resistance present in XL or XC 126
Figure 54: Zero sequence network showing residual currents 127
Figure 55: Practical case:- resistance present in XL and Xc 128
Figure 56: Non-directional SEF logic 130
Figure 57: EPATR B characteristic shown for TMS = 1.0 131
Figure 58: Resistive components of spill current 132
Figure 59: Operating characteristic for Icos 133
Figure 60: Directional SEF with VN polarisation (single stage) 134
Figure 61: Current distribution in an insulated system with C phase fault 135
Figure 62: Phasor diagrams for insulated system with C phase fault 136
Figure 63: Positioning of core balance current transformers 137
Figure 64: Cold Load Pickup logic 139
Figure 65: Selective Logic 141
Figure 66: Selecting the timer settings 142
Figure 67: Blocked Overcurrent logic 143
Figure 68: Blocked Earth Fault logic 144
Figure 69: Simple busbar blocking scheme 144
Figure 70: Simple busbar blocking scheme characteristics 145
Figure 71: 2nd Harmonic Blocking Logic (POC Input) 147
Figure 72: Start successful 148
Figure 73: Locked rotor detection 149
Figure 74: Reacceleration detection 150
Figure 75: Adjustable reacceleration authorization - Voltage restored within the set time 151
Figure 76: Adjustable reacceleration authorization - Voltage restored after the set time 152
Figure 77: Automatic restart authorized- voltage restored within the set time 153
Table of Figures P24xM
xviii P24xM-TM-EN-2.1