6.9.6 Monitored data
PID-3479-MONITOREDDATA v6
Table 98: BRCPTOC Monitored data
Name
Type Values (Range) Unit Description
IUNBAL REAL - - Measured unbalance of
phase currents
6.9.7 Operation principle
SEMOD171791-5 v5
Broken conductor check (BRCPTOC) detects a broken conductor condition by
detecting the asymmetry between currents in the three phases. The current-
measuring elements continuously measure the three-phase currents.
The current asymmetry signal output START is set on if:
• The difference in currents between the phase with the lowest current and the
phase with the highest current is greater than set percentage Iub> of the
highest phase current
• The highest phase current is greater than the minimum setting value IP>.
• The lowest phase current is below 50% of the minimum setting value IP>
The third condition is included to avoid problems in systems involving parallel
lines. If a conductor breaks in one phase on one line, the parallel line will
experience an increase in current in the same phase. This might result in the first
two conditions being satisfied. If the unsymmetrical detection lasts for a period
longer than the set time tOper the TRIP output is activated.
The simplified logic diagram of the broken conductor check function is shown in
figure
63
BRCPTOC is disabled (blocked) if:
• The IED is in TEST status and the function has been blocked from the local
HMI test menu (BlockBRC=Yes).
• The input signal BLOCK is high.
The BLOCK input can be connected to a binary input of the IED in order to receive
a block command from external devices, or can be software connected to other
internal functions of the IED itself to receive a block command from internal
functions.
The output trip signal TRIP is a three-phase trip. It can be used to command a trip
to the circuit breaker or for alarm purpose only.
Section 6 1MRK 505 384-UEN A
Current protection
160 Breaker protection REQ650 2.2 IEC
Technical manual
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