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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)
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
©2017 Siemens Protection Devices Limited
generators
Local
Generation
Non-essential
loads
Figure 1.5-1 Example Use of Alternative Settings Groups
7SR11 & 7SR12 Applications Guide
Start
RADIAL SUBSTATION
Trip non-essential loads
Select alternate
settings group
Chapter 7 Page 5 of 48
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