Basic Scheme - Siemens 7SR18 Solkor Manual

7SR18 Applications Guide
The relay closest to the fault (D) would step through its Instantaneous Trips in an attempt to clear the fault. If
unsuccessful, the relay would move to a Delayed Trip sequence.
The other relays in the network (A, B and C) would recognise the sequence of Pick-up followed by current switch-
off as AR sequences. They would therefore also step to their Delayed Trip to retain co-ordination with the
respective downstream devices.
The next Trip would be subject to current grading and Lockout the AR sequence such that the fault is cleared by
the correct CB.
8.1.1

Basic Scheme

Simple auto-reclose scheme with different local and remote dead-times.
If local relay fails it will not stop remote relay from operating e.g. No inhibit from local relay.
Figure 8.1.1-1 Events pulses
Figure 8.1.1-2 Sequence of events
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