16.7.2.2 Weak-end infeed logic
M15285-6 v5
Figure
376 shows a typical system condition that can result in a missing operation.
Note that there is no fault current from node B. This causes that the IED at B
cannot detect the fault and trip the breaker in B. To cope with this situation, a
selectable weak-end infeed logic is provided for the permissive overreaching
scheme.
A
B
IEC99000054-3-en.vsd
Strong
source
Weak
source
IEC99000054 V3 EN-US
Figure 376: Initial condition for weak-end infeed
16.7.3 Setting guidelines
IP15042-1 v1
M13933-4 v5
The parameters for the current reversal and weak-end infeed logic for residual
overcurrent protection function are set via the local HMI or PCM600.
Common base IED values for primary current (IBase), primary voltage (UBase)
and primary power (SBase) are set in a Global base values for settings function
GBASVAL.
GlobalBaseSel: It is used to select a GBASVAL function for reference of base
values.
16.7.3.1 Current reversal
M13933-6 v5
The current reversal function is set on or off by setting the parameter CurrRev to
On or Off. Time delays shall be set for the timers tPickUpRev and tDelayRev.
tPickUpRev is chosen shorter (<80%) than the breaker opening time, but minimum
20 ms.
tDelayRev is chosen at a minimum to the sum of protection reset time and the
communication reset time. A minimum tDelayRev setting of 40 ms is
recommended.
The reset time of the directional residual overcurrent protection (EF4PTOC) is
typically 25 ms. If other type of residual overcurrent protection is used in the
remote line end, its reset time should be used.
The signal propagation time is in the range 3 – 10 ms/km for most types of
communication media. In communication networks small additional time delays
are added in multiplexers and repeaters. Theses delays are less than 1 ms per
process. It is often stated that the total propagation time is less than 5 ms.
1MRK 506 369-UEN B Section 16
Scheme communication
Line distance protection REL670 2.2 IEC 725
Application manual
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