Siemens Argus 7SR21 Technical Manual page 597

Contents
Document Release History ............................................................................................................... 2
Software Revision History ................................................................................................................ 2
Section 1: Common Functions ......................................................................................................... 5
1.1 Multiple Settings Groups ...................................................................................................... 5
1.2 Binary Inputs ........................................................................................................................ 6
1.3 Binary Outputs ..................................................................................................................... 9
1.4 LEDs .................................................................................................................................... 9
Section 2: Protection Functions ..................................................................................................... 11
2.1 Time delayed overcurrent (51/51G/51N) ............................................................................. 11
2.1.1 Selection of Overcurrent Characteristics................................................................. 12
2.1.2 Reset Delay ........................................................................................................... 13
2.2 Voltage dependent overcurrent (51V) ................................................................................. 14
2.3 Cold Load Settings (51c) .................................................................................................... 14
2.4 Arc Flash Detection (50AFD) .............................................................................................. 15
2.5 Instantaneous Overcurrent (50/50G/50N) ........................................................................... 16
2.5.1 Blocked Overcurrent Protection Schemes .............................................................. 16
2.6 Sensitive Earth-fault Protection (50SEF) ............................................................................. 18
2.7 Directional Protection (67) .................................................................................................. 19
2.8 Directional Earth-Fault (50/51G, 50/51N, 51/51SEF)........................................................... 22
2.9 High Impedance Restricted Earth Fault Protection (64H) .................................................... 23
2.10 Negative Phase Sequence Overcurrent (46NPS)................................................................ 25
2.11 Undercurrent (37) ............................................................................................................... 25
2.12 Thermal Overload (49) ....................................................................................................... 25
2.13 Under/Over Voltage Protection (27/59) ............................................................................... 26
2.14 Neutral Overvoltage (59N) .................................................................................................. 27
2.14.1 Application with Capacitor Cone Units .................................................................... 28
2.14.2 Derived NVD Voltage ............................................................................................. 28
2.15 Negative Phase Sequence Overvoltage (47) ...................................................................... 28
2.16 Under/Over Frequency (81) ................................................................................................ 29
2.17 Power Protection ................................................................................................................ 30
2.17.1 Power (32) ............................................................................................................. 30
Section 3: CT Requirements ........................................................................................................... 31
3.1 CT Requirements for Overcurrent and Earth Fault Protection ............................................. 31
3.1.1 Overcurrent Protection CTs .................................................................................... 31
3.1.2 Earth Fault Protection CTs ..................................................................................... 31
3.2 CT Requirements for High Impedance Restricted Earth Fault Protection ............................. 31
Section 4: Control Functions.......................................................................................................... 32
4.1 Auto-reclose Applications ................................................................................................... 32
4.1.1 Auto-Reclose Example 1 ........................................................................................ 33
4.1.2 Auto-Reclose Example 2 (Use of Quicklogic with AR) ............................................ 34
4.2 Quick Logic Applications .................................................................................................... 35
4.2.1 Auto-Changeover Scheme Example ...................................................................... 35
Section 5: Supervision Functions .................................................................................................. 36
5.1 Circuit-Breaker Fail (50BF) ................................................................................................. 36
5.1.1 Settings Guidelines ................................................................................................ 36
5.2 Current Transformer Supervision (60CTS).......................................................................... 38
5.3 Voltage Transformer Supervision (60VTS).......................................................................... 39
5.4 Trip-Circuit Supervision (74TCS) ........................................................................................ 40
5.4.1 Trip Circuit Supervision Connections ...................................................................... 40
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7SR210 & 7SR220 Applications Guide
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