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7SG13 Delta P20064 FM1 Autoreclosing
Section 2: Element Definitions
2.1 Auto-reclose control
Delayed Auto-Reclose (DAR) is initiated by a valid trip relay operation while the associated circuit breaker is in
service.
A circuit breaker's service status is determined by its position. The circuit breaker is defined as being in service
when it is closed. The in service status has a drop-off delay of 2 sec, this delay is known as the circuit memory
time. This functionality prevents autoreclosing when the line is normally de-energised, or normally open.
The transition from DAR started to initiate deadtime takes place when the CB has opened; and the trip relay has
reset. If any of these do not occur within the Sequence Fail time the relay will Lockout. This is provided to prevent
the DAR being primed indefinitely, or the timer can be switched OFF.
Once a DAR sequence had been initiated, up to 4 unsuccessful recloses (where a closure is followed by a re-trip)
may be performed before the DAR feature is locked-out. Each reclosure is preceded by a time delay (dead time)
to give transient faults time to clear.
Once a CB has reclosed and remained closed for a specified time period (the Reclaim time), the DAR feature is
re-initialised and a Successful Close output issued. A single, common Reclaim time is used.
A count is kept of how many recloses have been performed.
Once lockout has occurred, an alarm is issued and all further Close commands, except manual close, are
inhibited for a specified time period (the Minimum Lockout time). A single, common lockout time is used. Lockout
can be latched until reset – see Lockout 2.1.14.
There are separate dead-time settings for each of the 4 recloses.
2.1.1 Protection Trip
The protection element which trips the CB is used to prime and start the autoreclose sequence.
Internal
protection elements that will start the A/R are pre-selected within the relay.
2.1.2 Protection Starter
If, during a sequence, the breaker is closed from another device and a fault is still on the system the starter
element will be energised. This is used to allow multi-shot autoreclose sequences to be co-ordinated for adjacent
relays, i.e. the number of shots can be kept in step.
2.1.3 External A/R Start
An External A/R Start can be received via a status input. A separate protection device would normally initiate this.
An External A/R Start will be treated the same as a Protection A/R Start by the Relay.
2.1.4 Manual Close
An External Close Command can be received via a status input or communications. This would normally be
initiated manually. It causes an instantaneous closure, over-riding any DAR sequence then in operation.
An External Close will initiate Line Check. If a fault appears on the line during the Close Pulse or the Reclaim
Time with Line Check set, the Protection relay will initiate a Trip and the A/R relay will Lockout. This prevents a
CB being repeatedly closed onto a faulted line.
Repeated Manual Closes are avoided by checking for Positive edge triggers. Even if the Manual Close input is
constantly energised the relay will only attempt one close. No Close Pulse will be issued when the Manual Close
input is reset.
Manual Close resets Lockout, if the conditions that set Lockout have reset i.e. there is no trip or Lockout input
present.
Manual Close cannot proceed if there is a Lockout input or Block Reclose input present.
With the Autoreclose function set to Out of Service the Manual Close control is still active.
©2010 Siemens Protection Devices Ltd.
P20064 Page 4 of 7
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