Auto Reclose Sequences; Figure 4.1-1 Typical Auto Reclose Sequence With 3 Instantaneous And 1 Delayed Trip - Siemens 7SR224 Description & Operation

(1) Description of Operation 7SR224

Auto Reclose sequences

The CONTROL & LOGIC>AUTO RECLOSE PROT'N and CONTROL & LOGIC>AUTORECLOSE
CONFIG' menus, allow the user to set independent Protection and Auto Reclose sequences for each
type of fault i.e. Phase Fault (P/F), Earth Fault (E/F), Sensitive Earth Fault (SEF) or External
Protections (EXTERN). Each Auto Reclose sequence can be user set for up to four-shots i.e. five trips
+ four reclose sequence, with independently configurable type of Protection Trip, either Fast (Inst) or
Delayed with associated Deadtime Delay time for each shot. The user has programming options for
Auto Reclose Sequences up to the maximum shot count i.e.:-
Inst or Delayed Trip 1 + (DeadTime 1: 0.1s-14400s)
+ Inst or Delayed Trip 2 + (DeadTime 2: 0.1s-14400s)
+ Inst or Delayed Trip 3 + (DeadTime 3: 0.1s-14400s)
+ Inst or Delayed Trip 4 + (DeadTime 4: 0.1s-14400s)
+ Inst or Delayed Trip 5 – Lockout.
The AR function recognizes developing faults and, as the shot count advances, automatically applies
the correct type of Protection Trip and associated Dead time for that fault-type at that point in the
sequence.
A typical sequence would consist of two Inst trips followed by at least one combined Delayed +
HighSet (HS) Trip. This sequence enables transient faults to be cleared quickly by the Inst trip(s) and
permanent fault to be cleared by the combined Delayed trip. The delayed trip must be 'graded' with
other Recloser/CB's to ensure system discrimination is maintained, i.e. that as much of the system as
possible is live after the fault is cleared.
A HS trips to lockout setting is provided such that when the number of operations of elements
assigned as HS trips reach the setting the relay will go to lockout.
The number of Shots (Closes) is user programmable, note: - only one Shot Counter is used to
advance the sequence, the Controller selects the next Protection characteristic/Dead time according
to the type of the last Trip in the sequence e.g. PF, EF, SEF or EXTERNAL.
Reclose Dead Time
User programmable dead times are available for each protection trip operation.
The dead time is initiated when the trip output contact reset, the pickup is reset and the CB is open.
The CB close output relay is energised after the dead time has elapsed.
st
1 Trip (Inst)
st
1 Dead Time

Figure 4.1-1 Typical Auto Reclose Sequence with 3 Instantaneous and 1 Delayed trip

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rd
nd
3 Trip (Inst)
2 Trip (Inst)
nd
2 Dead Time
3
th
4 Trip (Delayed)
rd
th
Dead Time
4
©2009 Siemens Protection Devices Limited
Dead Time