Auto Reclose Sequences - Siemens 7SG11 Manual

7SG11 Argus Technical Reference
the system restored. The Delay trips ensure that, if the instantaneous trips do not clear the fault i.e. it is
permanent, grading of the protections in series on the system occurs and the protection closest to the fault will trip
and isolate the fault.
2.9.1

Auto Reclose Sequences

The AUTO RECLOSE MENU enables the user to programme independent auto-reclose sequences for phase-fault,
earth-fault, sensitive earth-fault, and/or auto-reclose initiation from an external protection trip via a status input
mapped to STATUS CONFIG:ARC Status A (SA). For each sequence the user can select the optimum sequence
settings i.e. each trip can be selected to be either INSTantaneous or DELAYed with different Dead Times before
Reclosure for each shot. The User can set the required Sequence and number of Instantaneous trips and
Delayed trips to LockOut, the number of shots (Recloses) to LockOut, the number of High Set 1 Instantaneous
trips to LockOut and the number of High Set 2 trips to LockOut, allowed to achieve maximum retention/availability
of the power system. After each trip the relay determines its next course of action using the User settings. The
correct Auto–Reclose delay and Protection Characteristic response is applied after each trip in response to the
type of fault cleared, thus the correct sequence is applied at each stage of a developing fault.
Note:- in the AUTO RECLOSE:P/F Protection Trip: settings, INST refers to Instantaneous LowSet and not to
instantaneous HighSet. Also all protection elements operate in parallel, therefore, the first non-inhibited element,
that is mapped to trip, to time out will generate a trip output. The Delay and HighSet elements 1 & 2 can be used
together to provide a composite characteristic with IDMTL/DTL operation at low fault levels and higher speed
operation at higher fault levels to grade with fuses etc.
Sequence Co-ordination of the Instantaneous (Lowset) and Delayed protection operation of two relays in series
on a feeder is automatically provided if the upstream Lowset Instantaneous has a grading delay set. Grading
between both relays' Lowsets will be maintained and both upstream and downstream protections will keep their
shot counters in-step throughout a sequence; the upstream protection will apply the same sequence of
INST/DELAY protection, grading with the downstream CB on each shot and not tripping, thus the downstream CB
performs all the necessary trips to clear the fault.
To monitor the Circuit Breaker position the relay uses two Status inputs, mapped to the STATUS CONFIG:CB Open
and STATUS CONFIG:CB Closed settings, and Fault current monitoring to determine if the circuit breaker is open or
closed. If the CB is closed, or its state indeterminate due to interlock failure producing conflicting inputs, a reclose
Close pulse output will be inhibited, but a Manual Close & Reclaim or Remote Close & Reclaim Close pulse output is
always allowed.
The AUTO-RECLOSE:P/F ARC, AUTO-RECLOSE:E/F ARC, AUTO-RECLOSE:SEF ARC and AUTO-RECLOSE:SA ARC - IN/OUT
settings enable auto-reclose to be independently selected ON or OFF for each fault type. When ARC is set to IN
(On) i.e. switched into service, each setting can be overridden to OUT (Off) via a raised mapped status input
STATUS CONFIG:P/F ARC Off etc., or by being set to Off via the communications link commands. Overall All ARC
On/Off may also be set via the Relay's Linesman Mode:ARC ON/OFF setting (see section 2.14.2) or via a
communications link AutoReclose OFF command.
At significant stage points during an auto reclose sequence the relay logs and sends named events via the
communications link, with raised or cleared status as applicable. These named events greatly assist the user in
the process of determining the timing and exact sequence of events and the relay's response to system fault
conditions. The relay also indicates the status and progress of the auto reclose sequence via its ARC Status and
ARC Inhibits Instruments.
2.9.1.1 Protection and Auto Reclose Sequences
The following clauses describe the functionality of each setting in the Auto Reclose Menu for the Phase Fault
sequence. Identical settings and comments apply to the Earth Fault, Sensitive Earth Fault, and External Arc Start
via Status ARC start (SA) sequences. Each Settings Group G1, G2...G8 can have different Auto Reclose
sequence settings, or none, applied by the User.
Gn Line Check Trip = ON/OFF
The Auto-reclose:Line Check Trip setting allows this function to be enabled (ON) or dis-enabled (OFF) and is applied to
all Groups (G1 to G8) and all Sequences i.e. P/F, E/F, SEF & SA.
With Auto-reclose:Line Check Trip = ON, if the circuit breaker is closed via a Close pulse from the relay in response to
a raised 'Local Close & Reclaim' or a 'Remote Close & Reclaim' command raised via a mapped status input, or
communications command, or from the Linesman menu Linesman Mode:Close & Reclaim (section 2.14.2); then the
Line Check Trip (switch on to fault) function is activated and remains activated until the Reclaim Timer resets.
The Line Check function ensures that if the circuit breaker is closed onto a permanent fault, or if the circuit
breaker closes onto a healthy line but a fault then develops within the Auto-reclose:Reclaim Time setting, that the
relay will perform only one trip to Lockout, The relay will trip but it will not reclose nor go through an auto reclose
sequence.
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