Sel 751A - Station DC Battery Voltage Dips Anytime; Station DC Battery Voltage Dips During Circuit Breaker Closing; Breaker Monitor

5.15
Date Code 20100129 Instruction Manual SEL-751A Relay
Metering and Monitoring
Breaker Monitor
Station DC Battery Voltage Dips During Circuit Breaker Closing
To generate an event report when the SEL-751A closes the circuit breaker,
make the SEL
OGIC control equation event report generation setting:
ER = R_TRIG(OUT102) OR…
In this example, output contact OUT102 is set to close:
OUT102 = CLOSE (CLOSE is the logic output of Figure 4.30)
Anytime output contact OUT102 closes and energizes the circuit breaker close
coil, any dip in station dc battery voltage can be observed in column Vdc in
the event report.
This event report generation setting (ER = R_TRIG(OUT102) OR....) might
be made just as a testing setting. Generate several event reports when doing
circuit breaker close testing and observe the “signature” of the station dc
battery voltage in column Vdc in the event reports.
Station DC Battery Voltage Dips Anytime
To generate an event report anytime there is a station dc battery voltage dip,
set the dc voltage element directly in the SEL
OGIC control equation event
report generation setting:
ER = F_TRIG(SVnT) OR...
Timer output SVnT is an example dc voltage element from the bottom of
Figure 5.16. Anytime dc voltage falls below pickup DCHIP, timer output
SV4T drops out (logical 1 to logical 0 transition), creating a falling-edge
condition that generates an event report. Also, the Sequential Event Recorder
(SER) report can be used to time-tag station dc battery voltage dips.
Breaker Monitor
The breaker monitor in the SEL-751A helps in scheduling circuit breaker
maintenance. The breaker monitor is enabled with the enable setting:
EBMON = Y
The breaker monitor settings in Tabl e 5 .10 are available via the SET G
commands (see Table 6. 3). Also refer to BRE Command (Breaker Monitor
Data) on page 7.21 and BRE n Command (Preload/Reset Breaker Wear) on
page 7.21.
The breaker monitor is set with breaker maintenance information provided by
circuit breaker manufacturers. This breaker maintenance information lists the
number of close/open operations that are permitted for a given current
interruption level. The following is an example of breaker maintenance
information for a 25 kV circuit breaker. The breaker maintenance information
in Table 5.9 is plotted in Figure 5.17.