Specifications

7SR242 Duobias Description Of Operation

3.4 Current Protection: Measured Earth Fault (50G, 51G)

The earth current is measured directly via dedicated current analogue inputs. These optional elements utilise

either RMS or Fundamental current values as defined by the 51G/50G Measurement setting (MEASURED E/F

menu).

3.4.1 Instantaneous Measured Earth Fault Protection (50G)

Optionally two instantaneous measured earth fault elements are provided, each can be selected to either winding

1 or winding 2.

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.

Operation of the instantaneous measured earth fault elements can be inhibited from:

Inhibit 50G-n A binary or virtual input.

50G-n Inrush Action: Inhibit Operation of the inrush detector function.

Figure 3-9 Logic Diagram: Measured Instantaneous Earth-fault Element