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

Figure 3.3-1
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
79 E/F Inst Trips: 50G-n
50G-n Inrush Action: Inhibit
50G-n VTSAction: Inhibit

Figure 3.3-2 Logic Diagram: Measured Instantaneous Earth-fault Element

©2009 Siemens Protection Devices Limited
Logic Diagram: Measured Directional Earth Fault Protection
A binary or virtual input, or function key
When 'delayed' trips only are allowed in the auto-reclose
sequence (79 E/F Prot'n Trip n = Delayed).
Operation of the current inrush detector function.
Operation of the VT Supervision function.
(1) Description of Operation 7SR224
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