Siemens 7SR18 Solkor - Figure 3.1.1-2 Biased Differential Characteristic (Offset Enabled - Default); Figure 3.1.1-3 Logic Diagram: Biased Current Differential Protection

7SR18 Description Of Operation
Unrestricted ©2018 Siemens Protection Devices Limited Page 29 of 78
Figure 3.1.1-2 Biased Differential Characteristic (Offset Enabled - Default)
The 87L-1 Offset setting can be Enabled and is a historical Reyrolle method used to introduce more stability.
Operation of the biased differential elements can be inhibited from:
Inhibit 87L-n A binary or virtual input.
User Inhibit Reylogic (graphical logic).
The phase independent reversal feature Gn Phase-n Reversal in the CT/VT Config Menu is defaulted to
Disabled and is intended for use where CTs have been connected incorrectly.
c
Pickup
Operate
1
1
General Pickup
87L-n
87L-n 1
st
Bias Slope Limit
Enable
87L-n 1
st
Bias Slope
87L-n Initial Setting
IL1
IL2
IL3
&
Inhibit 87L-n
87L-n Element
Enabled
Disabled
c
Pickup
Operate
c
Pickup
Operate
87L-n Delay
87L-n 2
nd
Bias Slope
A
B
C
User Inhibit 87L-n
IL1
IL2
IL3
Remote
Local
Phase
Reversal
Phase
Reversal
CT
Multiplier
CT
Multiplier
Prot Comms Fail
Inhibit 87L-n
Figure 3.1.1-3 Logic Diagram: Biased Current Differential Protection