Siemens Argus 7SR22 - Current Protection: Under-Current (37, 37 G & 37 SEF); Current Protection: Under-Current Guarded (37); Figure 3.9-1 Logic Diagram: Undercurrent Detector (37, 37 G & 37 SEF); Figure 3.10-1 Logic Diagram: Undercurrent Guarded Detector (37)

7SR210 & 7SR220 Description of Operation
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3.9 Current Protection: Under-Current (37, 37G & 37SEF)
Two under-current elements are provided for each 37, 37G & 37SEF protection function.
Each phase has an independent level detector and current-timing element. 37-n Setting sets the pick-up current.
An output is given after elapse of the 37-n Delay setting.
Operation of the under-current elements can be inhibited from: -
Inhibit 37-n A binary or virtual input, function key or remote data Comms
Figure 3.9-1 Logic Diagram: Undercurrent Detector (37, 37G & 37SEF)
3.10 Current Protection: Under-Current Guarded (37)
A level detector 37-n U/I Guard Setting sets the pick-up current.
Figure 3.10-1 Logic Diagram: Undercurrent Guarded Detector (37)