ensures the send signal from IED B2 is held back till the forward direction element is reset
in IED A2.
12.6.2.2 Weak-end infeed logic
Figure 201 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.
en99000054_ansi.vsd
LINE 1
A B
Strong
source
Weak
source
CLOSEDCLOSED
FAULT
ANSI99000054 V1 EN
Figure 201: Initial condition
12.6.3 Setting guidelines
The parameters for the current reversal and weak-end infeed logic for residual overcurrent
protection function are set via the local HMI or PCM600.
GlobalBaseSel: Selects the global base value group used by the function to define (IBase),
(VBase) and (SBase).
12.6.3.1 Current reversal
The current reversal function is set on or off by setting the parameter CurrRev to Enabled
or Disabled. 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.
Section 12 1MRK 506 334-UUS A
Scheme communication
410
Application manual
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