7SR18 Applications Guide
Unrestricted ©2018 Siemens Protection Devices Limited Page 7 of 63
Section 1: Common Functions
1.1 Multiple Settings Groups
Alternate settings groups can be used to reconfigure the relay during significant changes to system conditions
e.g.
Primary plant switching in/out
Summer/winter or day/night settings
Switchable earthing connections
Loss of Grid connection (see below)
Figure 1.1-1 Example Use of Alternative Settings Groups
RADIAL SUBSTATION
Start
generators
Select alternate
settings group
Local
Generation
Industrial system draws power from grid
system during normal operation
Relays normally use settings group 1
On loss of mains:
Local generation switched in.
Non essential loads tripped
Relays on essential circuits switched to
settings group 2 to reflect new load and
fault currents
Non-essential
loads
Trip non-essential loads
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