7SR11 & 7SR12 Commissioning and Maintenance Guide
ยฉ2017 Siemens Protection Devices Limited Chapter 6 Page 5 of 72
List of Figures
Figure 2-1 Directional Phase Fault Boundary System Angles ............................................................ 13
Figure 2-2 Phase Overcurrent ............................................................................................................. 14
Figure 2-3 Voltage Controlled Overcurrent ......................................................................................... 17
Figure 2-4 Cold Load ........................................................................................................................... 19
Figure 2-5 Cold Load Logic diagram ................................................................................................... 20
Figure 2-6 Arc Flash Detection ............................................................................................................ 23
Figure 2-7 Directional Earth Fault Boundary System Angles .............................................................. 24
Figure 2-8 Derived Earth Fault ............................................................................................................ 25
Figure 2-9 Measured Earth Fault ........................................................................................................ 29
Figure 2-10 Sensitive Earth Fault .......................................................................................................... 33
Figure 2-11 Restricted Earth Fault ........................................................................................................ 37
Figure 2-12 Negative Phase Sequence Overcurrent ............................................................................ 39
Figure 2-13 Undercurrent ...................................................................................................................... 42
Figure 2-14 Thermal Overload .............................................................................................................. 44
Figure 2-15 Phase Under/Over Voltage ................................................................................................ 46
Figure 2-16 NPS Overvoltage ............................................................................................................... 48
Figure 2-17 Neutral Overvoltage ........................................................................................................... 50
Figure 2-18 Under/Over Frequency ...................................................................................................... 52
Figure 2-19 Power ................................................................................................................................. 54
Figure 2-20 Sensitive Power ................................................................................................................. 56
Figure 2-21 Power Factor ...................................................................................................................... 58
Figure 2-22 CB Fail ............................................................................................................................... 60
Figure 2-23 Voltage Transformer Supervision ...................................................................................... 62
Figure 2-24 Current Transformer Supervision 7SR11 .......................................................................... 64
Figure 2-25 Current Transformer Supervision 7SR12 .......................................................................... 65
Figure 2-26 Broken Conductor .............................................................................................................. 66
Figure 2-27 Trip Circuit Supervision ...................................................................................................... 68
Figure 2-28 Magnetising Inrush Detector .............................................................................................. 69
List of Tables
Table 2-1 Troubleshooting Guide....................................................................................................... 72