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Reset Ratio.............................................................................................................................. 78
2.4.4
Miscellaneous functions ......................................................................................................... 78
2.4.5
Setting for Petersen coil earthed system.............................................................................. 79
2.4.6
Setting of standby earth-fault ............................................................................................... 80
2.4.7
Scheme logic ........................................................................................................................... 80
2.4.8
Setting ..................................................................................................................................... 83
2.4.9
Signal ...................................................................................................................................... 88
2.4.10
Negative sequence overcurrent protection (OCN) ...................................................................... 90
Relay polarity ......................................................................................................................... 90
2.5.1
Inverse time and definite time delay characteristic ............................................................ 92
2.5.2
Threshold value ...................................................................................................................... 98
2.5.3
Reset Ratio.............................................................................................................................. 98
2.5.4
Miscellaneous functions ......................................................................................................... 98
2.5.5
Scheme logic ........................................................................................................................... 99
2.5.6
Setting ................................................................................................................................... 101
2.5.7
Signal .................................................................................................................................... 106
2.5.8
Undercurrent protection (UC) .................................................................................................... 108
Operation and characteristic ............................................................................................... 109
2.6.1
Miscellaneous functions ....................................................................................................... 109
2.6.2
Scheme switch ...................................................................................................................... 109
2.6.3
Setting .................................................................................................................................... 111
2.6.4
Signal .................................................................................................................................... 112
2.6.5
Switch on to fault (SOTF-OC) .................................................................................................... 113
Scheme logic ......................................................................................................................... 113
2.7.1
Setting ................................................................................................................................... 115
2.7.2
Signal .................................................................................................................................... 115
2.7.3
Broken conductor protection (BCD) ........................................................................................... 116
Equivalent circuit for a one-phase series fault .................................................................. 117
2.8.1
Characteristic and setting ................................................................................................... 119
2.8.2
Miscellaneous functions ....................................................................................................... 119
2.8.3
Scheme logic ......................................................................................................................... 120
2.8.4
Setting ................................................................................................................................... 121
2.8.5
Signal .................................................................................................................................... 121
2.8.6
Thermal overload function (THM) ............................................................................................. 122
Thermal state determination .............................................................................................. 123
2.9.1
Thermal characteristic ........................................................................................................ 124
2.9.2
Scheme logic ......................................................................................................................... 125
2.9.3
Setting ................................................................................................................................... 126
2.9.4
Signal .................................................................................................................................... 126
2.9.5
vii
6F2T0207 (0.01)
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