Arcteq AQ-F210, Инструкция по эксплуатации

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Instruction manual –AQ F210 Feeder Protection IED 161 (292
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4.3.3 A
UTO
-
RECLOSING
0

1 (79)
Autoreclosing (AR) means coordinated de-energisation and energisation of transmission or
distribution overhead-line with purpose to clear permanent or semi-permanent cause of fault
from the line in order to restore supply automatically to the line.
Autoreclosing can be used in overhead-line networks for clearing transient and semi-
permanent faults which present approximately 80-95% of all of the faults found in
transmission and distribution networks. Majority of this type of faults can be cleared with
high speed autoreclosing and the rest of the faults can be cleared with delayed
autoreclosing by de-energizing the faulty line for a longer period of time.
Only minority of the overhead line faults are permanent type which require maintenance or
repair in the actual fault location. Faults like lightning in the line, tree branch touching to the
overhead line, arc caused by animals or short circuits caused by objects touching to the
overhead lines are this type of transient and semi-permanent faults. If the fault is permanent
for example tree fall and leaning into the overhead line or broken insulator, autoreclosing
will not clear the fault and the faulty feeder shall be locked from closing until the cause of
the fault is repaired in the actual fault location. Also close short circuit faults should avoid
the autoreclosing to be even initiated in order to avoid unnecessary stress for the lines and
circuit breaker in cases when the fault cannot be cleared by autoreclosing the line. Similar
situations arise also in the mixed cable and overhead line networks since cable network
faults cannot be cleared by autoreclosing. In this category faults the autorecloser should be
aware of fault location before autoreclosing is applied to the faulty line.
4.3.3.1 A
UTORECLOSING AS APPLICATION
The main principle of autoreclosing is to de-energize the faulty line and fault location so that
the cause of the fault can drop out from the line. When the line is energized and object
either touches or drops into the line, current will start to flow through the object either to the
ground or in between of the phases causing the surrounding air to heat and ionize and start
to operate as conductor in between of the energized phase(s) and (or) ground causing arc
to ignite.
When the breaker is opened either by command of autorecloser or protection function,
voltage in the line will be zero thus extinguishing the arc and letting the object which caused
the fault to drop from the line and by this way clearing the cause of the fault. Autorecloser
closes the breaker after set time (called Dead Time meaning the time which the line is not-
energized) and the supply is restored to the line. If the fault is not cleared by this first
autoreclosing cycle (called Shot) then more shots can be applied to the line.