Basler BE1-CDS220, Инструкция по эксплуатации

Страница: 228 / 476

8-50 Application BE1-CDS220
Table 8-31. Miscellaneous Logic Expressions
Command Reference
SA-RESET Section 6, Reporting and Alarm Functions, Alarms Function
SB-DUTY Section 6, Reporting and Alarm Functions, Breaker Monitoring
SB-LOGIC Section 6, Reporting and Alarm Functions, Breaker Monitoring
SG-TARG Section 6, Reporting and Alarm Functions, Fault Reporting
SG-TRIGGER Section 6, Reporting and Alarm Functions, Fault Reporting
ST-DUTY Section 6, Reporting and Alarm Functions, Transformer Monitoring
APPLICATION TIPS
Trip Circuit Continuity and Voltage Monitor
The trip circuit monitor drives logic variable CKTMON. This variable can be used to improve breaker
failure logic or to automatically enhance security during testing.
If the relay detects a loss of voltage or continuity in the breaker trip circuit, it is possible to speed up fault
clearing time by bypassing the breaker failure timer. Since relay failure and breaker failure are covered by
different backup actions, it is desirable to reduce common mode failure mechanisms. It is recommended
that the feeder breaker and feeder protection circuits be supplied by separate control power fuses or
breakers. The equation for the Breaker Failure Trip logic (VO5) in Figure 8-16 can be modified by ORing
the Breaker Failure Trip output with the expression VO10
∗
CKTMON. VO10 is designated as the Breaker
Failure Initiate expression. Example 1 illustrates how the BFT logic expression is modified. It is important
that the breaker failure timer bypass logic also be disabled in test mode. Example 2 shows the expression
for blocking the upstream instantaneous element. Figure 8-16 illustrates using the trip circuit continuity
monitor in breaker failure logic.
Example 1: Breaker failure trip expression:
SL-VO5=BFT+VO10*CKTMON*IN4*/343
Example 2: Block upstream instantaneous expression:
SL-VO4=VO12*/VO5*/CKTMON*IN4*/343
If the internal breaker failure function block is not being used, the trip circuit continuity and voltage monitor
alarm can be used to detect when the test switches have been opened. This will automatically place the
relay in the test mode. Each of the preprogrammed logic schemes has logic to detect when the relay is out
of service for test. This enables the backup logic and enhances security. It should be noted that if the test
mode logic is modified in this manner, it is not possible to differentiate between the relay being out of
service for test and a problem in the circuit breaker trip circuit. Otherwise, the internal breaker failure
function block would be disabled during a known problem in the trip circuit.