Chapter 1) 7SR242 Duobias Description Of Operation
©2015 Siemens Protection Devices Limited
Chapter 1 Page 26 of 60
3.1.3 87HS
W2
W1
I
I
2
I
I
W2
W1
Figure 3-3 Differential Highset Characteristic
Figure 3.1-3 illustrates the differential highset characteristic. Within the relay the fundamental frequency RMS line
currents are modified by the
ICT Multiplier
and
ICT Connection
settings (see 3.1.1) before being applied to the
differential highset elements. The differential highset elements calculate the operate current for each phase from
the vector sum of winding 1 and winding 2 currents i.e. I
OPERATE
= I
W1
+ I
W2
.
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.
87HS Inrush Action: Inhibit
Operation of the inrush current detector
87HS Overfluxing Action: Inhibit
Operation of the overfluxing detector
User Inhibit
Reylogic (graphical logic).
Summary of Contents for 7SR242 Duobias
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