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D2110075_EN.fm Page 12 Vendredi, 3. septembre 2004 8:58 08
Operation
As soon as Flair 3xx is operational, it will display alternatively
the 3 fault counters (see paragraph “Fault counters”) and be
ready for detecting faults.
However, faults can only be detected if MV has been present
for more than 5 s (inrush restraint).
Identification of the fault type
Single phase-to-earth fault
Single phase-to-earth faults are identified by flashing
of a constant colour, either red or green, depending on
the fault location.
b Upstream the fault, each feeder FPI flashes.
b Downstream the fault, an FPI only flashes if the capacitive
current downstream this FPI is at least 30 A.
Note: a total capacitive current of 50 A is required to guarantee
detection of an earth fault in any part of the network.
Multi-phase faults
These faults are identified by an alternating green/red flashing.
All detectors placed upstream the fault, and only these ones,
flash.
Moreover, in both cases:
b the relevant counter is incremented by one unit,
b the relevant ouptput contact closes.
Based on this, the faulty section should be identified as explained
next page.
Indication reset
Indication reset (light and permanent faults output contact)
is performed under one of the hereunder conditions:
b automatically after a time duration configurable from 2 hours
to 16 hours,
b if MV is back and fault condition has disappeared i.e. residual
voltage is less than 0.18 Un for a time exceeding 5 s (only if
rStU = on: see paragraph “Parameters and default settings”),
b by action on the magnetic RESET / + button.
The signalling reset:
b causes light indication to stop,
b opens the output contact (see paragraph “Output contact
behaviour” for more details),
b preserves counter incrementation.
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