iv 9424200994 Rev N
Frequency (81) Protection ........................................................................................................................ 79
Frequency Measurement......................................................................................................................... 79
Underfrequency and Overfrequency Protection ...................................................................................... 79
Frequency Rate-of-Change Protection .................................................................................................... 80
Logic Connections ................................................................................................................................... 82
Operational Settings ................................................................................................................................ 82
Negative-Sequence Overcurrent (46) Protection ................................................................................... 85
Pickup Settings ........................................................................................................................................ 85
Coordination Settings .............................................................................................................................. 86
Instantaneous Overcurrent (50) Protection ............................................................................................ 87
Element Operation ................................................................................................................................... 87
Logic Connections ................................................................................................................................... 88
Operational Settings ................................................................................................................................ 89
Breaker Failure (50BF) Protection ........................................................................................................... 91
Element Operation ................................................................................................................................... 91
Logic Connections ................................................................................................................................... 92
Operational Settings ................................................................................................................................ 93
Inverse Overcurrent (51) Protection ........................................................................................................ 95
Element Operation ................................................................................................................................... 95
Logic Connections ................................................................................................................................. 100
Operational Settings .............................................................................................................................. 100
Directional Overcurrent (67) Protection ................................................................................................ 103
Polarization Methods ............................................................................................................................. 103
Maximum Torque Angle and Directional Tests ..................................................................................... 105
Theory of Using Sequence Impedances for Fault Direction .................................................................. 106
Phase Current Differential (87) Protection ........................................................................................... 109
Element Operation ................................................................................................................................. 109
Logic Connections ................................................................................................................................. 112
Settings .................................................................................................................................................. 113
Neutral Current Differential (87N) Protection ....................................................................................... 117
Element Operation ................................................................................................................................. 117
Logic Connections ................................................................................................................................. 119
Operational Settings .............................................................................................................................. 120
Phase Differential Protection: Self-Balancing and Split-Phase Configurations (50/51) .................. 121
Power (32) Protection ............................................................................................................................. 123
Element Operation ................................................................................................................................. 123
Logic Connections ................................................................................................................................. 126
Operational Settings .............................................................................................................................. 126
Loss of Excitation - Reverse Var Based (40Q) Protection .................................................................. 127
Element Operation ................................................................................................................................. 127
Logic Connections ................................................................................................................................. 128
Operational Settings .............................................................................................................................. 129
Distance (21) Protection ......................................................................................................................... 131
Element Operation ................................................................................................................................. 131
Logic Connections ................................................................................................................................. 132
Operational Settings .............................................................................................................................. 132
Loss of Excitation - Impedance Based (40Z) Protection ..................................................................... 135
Element Operation ................................................................................................................................. 135
Logic Connections ................................................................................................................................. 136
Operational Settings .............................................................................................................................. 137
Typical Application ................................................................................................................................. 138
Contents BE1-11g
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