Siemens 7SR242 Duobias - Page 4

7SR242 Duobias Commissioning & Maintenance Guide
©2010 Siemens Protection Devices Limited Chapter 6 Page 4 of 57
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