Siemens 7SR18 Solkor - Current Protection: Line Check 50 LC, 50 G LC; Figure 3.9-1 Logic Diagram: Thermal Overload Protection (49); Figure 3.10-1 Logic Diagram: 50 G Line Check Elements (50 G LC); Figure 3.10-2 Logic Diagram: 50 Line Check Elements (50 LC)

7SR18 Description Of Operation
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Figure 3.9-1 Logic Diagram: Thermal Overload Protection (49)
3.10 Current Protection: Line Check 50LC, 50G LC
This feature prevents a CB being repeatedly manually closed onto a faulted line. It is enabled upon the
Manual CB Close output being issued. If a fault is detected following closure, the Relay will trip for
Line Check. A fault is detected if the measured current is above the LC-n Setting level for a period
greater than the LC-n Delay.
Two line check elements are provided, LC-1 and LC-2, for each fault type - phase and earth – in the
CURRENT PROT’N > LINE CHECK menu.
The feature will remain enabled until the CB has been closed for a duration equal to the Close CB
Pulse + Reclaim Timer (AR option) settings in the CIRCUIT BREAKER MENU. Alternatively, the
element will remain enabled as long as the Line Check binary input is energised.
Figure 3.10-1 Logic Diagram: 50G Line Check Elements (50G LC)
Figure 3.10-2 Logic Diagram: 50 Line Check Elements (50LC)