ABB RER670 - Application

13.2.2 Application
IP15023-1 v1
13.2.2.1 Current reversal logic
M13895-4 v6
In the case of parallel lines, overreaching permissive communication schemes can
cause unwanted tripping due to current reversal. The unwanted tripping affects the
healthy line when a fault is cleared on the parallel line. This lack of security results
in a total disconnection between the two buses.
To avoid this kind of disturbances, a fault current reversal logic (transient blocking
logic) can be used.
The unwanted operations that might occur can be explained by looking into
Figure 147 and Figure 148. Initially 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
IEC9900043-2.vsd
IEC99000043 V3 EN-US
Figure 147: 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
IEC99000044-2.vsd
IEC99000044 V3 EN-US
Figure 148: Current distribution for a fault close to B side when breaker B1 has
opened
To handle this the send signal CS or CSLn from B2 is held back until the reverse
zone IRVLn has reset and the tDelayRev time has been elapsed. To achieve this the
reverse zone on the distance protection shall be connected to input IRV and the
output IRVL shall be connected to input BLKCS on the communication function
block ZCPSCH.
Section 13 1MRK 506 375-UEN A
Scheme communication
350 Railway application RER670 2.2 IEC
Application manual