ABB RELION REX640, Техническое руководство, Страница: 1278 / 1960

Figure 724: Fault occurs at one of the parallel lines. CS=carrier signal sending, CR=carrier signal
receiving
The faulty feeder (Feeder 1) is not simultaneously tripped at both ends and, for
example, the circuit breaker closer to the fault at Relay B1 may be tripped faster than
the breaker at bus A. As a result, when the breaker at Relay B1 opens, the direction of
the fault current at the healthy feeder (Feeder 2) is reversed.
Figure 725: Circuit breaker at Relay B1 opens and creates a current reversal condition. CS=carrier signal
sending, CR=carrier signal receiving
Relay A2 still sends the CS signal because of the reset time delay of the forward
direction residual overcurrent function of Relay A2. When Relay B2 starts to
recognize the fault in the forward direction, Relay B2 can malfunction and trip the
breaker of the healthy feeder.
This problem can be solved using the reverse directional residual overcurrent
function to recognize the fault in reverse direction and temporarily block the
operation of the scheme communication logic due to the current reversal condition.
This is used in RCRWPSCH.
Protection related functions 1MRS759142 F
1278 REX640
Technical Manual