Specifications

7SR242 Duobias Commissioning & Maintenance Guide
©2010 Siemens Protection Devices Limited Chapter 6 Page 4 of 56
List of Figures
Figure 2-1 Biased Differential..............................................................................................................14
Figure 2-2 Secondary Injection using a Variac ...................................................................................15
Figure 2-3 Phase Overcurrent.............................................................................................................18
Figure 2-4 Measured Earth Fault ..........................................................................................................21
Figure 2-5 Measured Earth Fault ..........................................................................................................24
Figure 2-6 Restricted Earth Fault ..........................................................................................................27
Figure 2-7 Open Circuit..........................................................................................................................29
Figure 2-8 Negative Phase Sequence Overcurrent ...............................................................................31
Figure 2-9 Undercurrent.........................................................................................................................34
Figure 2-10 Thermal Overload ...............................................................................................................36
Figure 2-11 Phase Under/Over Voltage.................................................................................................38
Figure 2-12 Neutral Overvoltage............................................................................................................41
Figure 2-13 Under/Over Frequency .......................................................................................................43
Figure 2-14 Under/Over Frequency .......................................................................................................45
Figure 3-1 CB Fail ..................................................................................................................................47
Figure 3-2 Trip Circuit Supervision.........................................................................................................49
Figure 3-3 Magnetising Inrush Detector.................................................................................................50
Figure 3-4 Magnetising Inrush Detector.................................................................................................52