Signal
Range
Description
IndicatorX
Close
input
("Ind.X
Close
Status
In")
Digital input or other
logical signal selected
by the user
(SWx)
A link to a physical digital input. The monitored indicator's CLOSE status. "1" refers to
the active "Close" state of the monitored indicator. If IEC 61850 is enabled, GOOSE
signals can be used for status indication.
Events
The indicator object monitoring function (abbreviated "CIN" in event block names) generates events
from the status changes in the monitored signals, including the continuous status indications. The user
can select which event messages are stored in the main event buffer: ON, OFF, or both.
5.4.4 Auto-recloser (79)
Auto-reclosing means a coordinated de-energization and re-energization of overhead lines (both
transmission and distribution). Its purpose is to clear transient and semi-permanent fault causes from
the line and automatically restore the supply to the line. These types of faults account for approximately
80...95 % of all faults found in transmission and distribution networks. The majority of these fault types
can be cleared with high-speed auto-reclosing, while the rest can be cleared with delayed auto-
reclosing by de-energizing the faulty line for a longer period of time.
Only a minority of overhead line faults are of the permanent type which require maintenance or repair
in the actual fault location. This type of fault include lightning striking the line, a tree branch touching
the line, an arc caused by animals, and a short-circuit caused by some other object touching the line. If
the fault is permanent (e.g. a broken insulator or a fallen tree leaning on the overhead line), the auto-
recloser cannot clear the fault and the faulty feeder is locked and prevented from closing until the
cause of the fault is repaired in the actual fault location. Also, when a fault cannot be cleared by auto-
reclosing the line, any close-distance short-circuits should avoid initiating the auto-recloser because
that would only cause unnecessary stress for the lines and the circuit breakers. Similar situations also
rise in mixed networks since cable network faults cannot be cleared with the auto-recloser. The
function must therefore be aware of the fault location before applying the auto-recloser to the faulty
line.
Auto-recloser as application
The main principle of the auto-recloser is to de-energize the faulty line and the fault location so
the cause of the fault can drop out from the line. When the line is energized and an object either
touches the line or drops onto the line, the current starts to flow through the object either to the ground
or between the phases. This causes the surrounding air to heat and ionize, and it starts to operate as a
conductor between the energized phase(s) and the ground causing an arc to ignite.
When the breaker is opened (either by an auto-recloser command or by a protection function), the
voltage in the line goes to zero. This extinguishes the arc and lets the fault-causing object to drop from
the line, thus clearing the cause of the fault. Auto-reclosing closes the breaker after a set time (called
'dead time' during which the line is not energized) and the supply is restored to the line. If the fault is not
cleared by the first auto-recloser cycle (called 'shot'), more shots can be applied to the line.
Alternatively, the function can be set to initiate the final trip, locking the feeder closing. The decision
between a single-shot and a multi-shot auto-recloser depends on the following: protection type,
switchgear, circuit breaker, stability requirements, network type, consumer loads as well as local utility
knowledge and network practices.
A
AQ
Q-F215
-F215
Instruction manual
Version: 2.04
303
