Chapter 1) 7SR23 DAD Description Of Operation
©2013 Siemens Protection Devices Limited
Chapter 1 Page 19 of 36
3.3
Protection: Restricted Earth Fault (87REF)
Two 87REF elements are provided (87REF-1 and 87REF-2). 87REF-1 earth current is measured by the earth
current input, 87REF-2 current is measured by the I
B
current input. These elements utilise RMS current values of
the fundamental frequency (50 or 60Hz).
Two restricted earth fault elements are provided.
87REF-n Setting
defines the current required to operate the REF element. The output of 87
REF-n Delay
can be
mapped to relay outputs.
Operation of the REF-n element can be inhibited from:
Inhibit 87REF-n
A binary or virtual input.
User Inhibit
Reylogic (graphical logic)
Figure 3-4 Logic Diagram: Restricted Earth Fault Protection
Summary of Contents for 7SR23 DAD
Page 1: ...Answers for energy 7SR23 DAD High Impedance Protection Relay Reyrolle Protection Devices ...
Page 2: ......
Page 4: ...7SR23 DAD Contents 2013 Siemens Protection Devices Limited ...
Page 60: ...Chapter 3 7SR23 DAD Performance Specification 2013 Siemens Protection Devices Limited ...
Page 225: ......