Siemens 7SR224 - Instantaneous Measured Earth Fault Protection (50 G); Figure 3.3-1 Logic Diagram: Measured Directional Earth Fault Protection; Figure 3.3-2 Logic Diagram: Measured Instantaneous Earth-Fault Element

(1) Description of Operation 7SR224
©2009 Siemens Protection Devices Limited Page 25 of 66
Figure 3.3-1 Logic Diagram: Measured Directional Earth Fault Protection
3.3.2 Instantaneous Measured Earth Fault Protection (50G)
Four elements are provided e.g. giving the option of using two elements set to forward and two to
reverse.
Each instantaneous element has independent settings for pick-up current 50G-n Setting and a
follower time delay 50G-n Delay. The instantaneous elements have transient free operation.
For the directional elements the direction of operation can be set using 50G-n Dir. Control setting.
Directional logic is provided independently for each 50G-n element.
Operation of the instantaneous measured earth fault elements can be inhibited from:
Inhibit 50G-n A binary or virtual input, or function key
79 E/F Inst Trips: 50G-n When ‘delayed’ trips only are allowed in the auto-reclose
sequence (79 E/F Prot’n Trip n = Delayed).
50G-n Inrush Action: Inhibit Operation of the current inrush detector function.
50G-n VTSAction: Inhibit Operation of the VT Supervision function.
Figure 3.3-2 Logic Diagram: Measured Instantaneous Earth-fault Element