Siemens 7SR18 Solkor - Differential Highset (87 HS-N); Figure 3.1.2-1 Differential Highset Characteristic; Figure 3.1.2-2 Logic Diagram: Differential High Set Current Protection

7SR18 Description Of Operation
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3.1.2 Differential Highset (87HS-n)
Figure 3.1.2-1 Differential Highset Characteristic
The differential protection elements 87L-1 & 87L-2 each have an associated High Set element i.e. 87HS-1 &
87HS-2.
Figure 3.1.2-1 illustrates the differential highset characteristic. The differential highset elements calculate the
operate current for each phase from the vector sum of local relay and remote relay currents i.e. I
OPERATE
= I
L
+ I
R
.
87HS Setting defines the differential current required to operate the element. The output of 87HS Delay can be
mapped to relay outputs.
Operation of the highset differential elements can be inhibited from: -
Inhibit 87HS A binary or virtual input.
User Inhibit Reylogic (graphical logic).
Figure 3.1.2-2 Logic Diagram: Differential High Set Current Protection