Siemens 7SR18 Solkor - Instantaneous Overcurrent Protection (50); Figure 3.3.1-1 Logic Diagram: Directional Overcurrent Element (67)

7SR18 Description Of Operation
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(fwd)
fwd
rev
fwd
rev
fwd
rev
(rev)
L1 Fwd
L1 Rev
L3 Fwd
L2 Fwd
L3 Rev
L2 Rev
Directional
Control Signal
Figure 3.3.1-1 Logic Diagram: Directional Overcurrent Element (67)
3.3.2 Instantaneous Overcurrent Protection (50)
Up to four Instantaneous overcurrent elements are provided (depending upon variant): -
50-1, 50-2, 50-3 & 50-4
Each instantaneous element (50-n) has independent settings. 50-n Setting for pick-up current and 50-n Delay
follower time delay. The instantaneous elements have transient free operation.
Where directional elements are present the direction of operation can be set using 50-n Dir. Control setting.
Directional logic is provided independently for each 50-n element, e.g. giving the option of using two elements set
to forward and two to reverse.
Operation of the instantaneous overcurrent elements can be inhibited from:
Inhibit 50-n A binary or virtual input.
79 P/F Inst Trips: 50-n When ‘delayed’ trips only are allowed in the auto-reclose sequence
(79 P/F Prot’n Trip n = Delayed).
50-n Inrush Action: Block Operation of the inrush current detector function.
50-n VTS Action: Inhibit Operation of the VT Supervision function.