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15.4
Current reversal and weak-end infeed logic for phase
segregated communication ZC1WPSCH
SEMOD155635-1 v2
15.4.1
Identification
SEMOD156467-2 v2
Function description
IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Current reversal and weak-end
infeed logic for phase segregated
communication
ZC1WPSCH
-
85
15.4.2
Application
SEMOD156558-1 v1
SEMOD156537-5 v4
Current reversal logic
If parallel lines are connected to common buses at both terminals, overreaching permissive
communication schemes can trip unselectable due to current reversal. The unwanted tripping
affects the healthy line when a fault is cleared on the other line. This lack of security results in a
total loss of interconnection between the two buses.
To avoid this kind of disturbances, fault current reversal logic (transient blocking logic) can be
used.
The unwanted operations that might occur can be explained by looking into
. Assume that the fault has been taken place close to breaker B1. At first, the
protection A2 at A side will detect a fault in forward direction and send a communication
signal to the protection B2 at remote end, which is measuring a fault in reverse direction.
L1
L2
A1
A2
B1
B2
IEC14000002-1-en.vsd
IEC14000002 V1 EN-US
Figure 381: Current distribution for a fault close to B side when all breakers are closed
When the breaker B1 opens for clearing the fault, the fault current through B2 bay will invert. If
the communication signal has not reset at the same time as the distance protection function
used in the teleprotection scheme has switched on to forward direction, we will have an
unwanted operation of breaker B2 at B side.
L1
L2
A1
A2
B1
B2
IEC14000003-1-en.vsd
IEC14000003 V1 EN-US
Figure 382: Current distribution for a fault close to B side when breaker B1 is opened
To handle this, the send signal CS or CSLx from B2 is held back until the reverse zone IRVLx has
reset and the
tDelayRev time has elapsed. To achieve this, the reverse zone on the distance
1MRK 505 343-UEN B
Section 15
Scheme communication
613
Application manual
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