8.18
SEL-351A Relay Instruction Manual Date Code 20080213
Breaker Monitor and Metering
Station DC Battery Monitor (Not in SEL-351A-1)
Analyze Station DC
Battery Voltage
See Standard 15/30-Cycle Event Reports on page 12.2. The station dc battery
voltage is displayed in column
Vdc in the example event report in Figure 12.3.
Changes in station dc battery voltage for an event (e.g., circuit breaker
tripping) can be observed. Use the EVE command to retrieve event reports as
discussed in Section 12: Standard Event Reports and SER.
Station DC Battery Voltage Dips During Circuit Breaker Tripping
Event reports are automatically generated when the TRIP Relay Word bit
asserts (TRIP is the logic output of Figure 5.1). For example, output contact
OUT101 is set to trip:
OUT101 = TRIP
Anytime output contact OUT101 closes and energizes the circuit breaker trip
coil, any dip in station dc battery voltage can be observed in column Vdc in
the event report.
To generate an event report for external trips, make connections similar to
Figure 8.8 and program optoisolated input IN106 (monitoring the trip bus) in
the SEL
OGIC control equation event report generation setting, e.g.,
ER = /IN106 + ...
Anytime the trip bus is energized, any dip in station dc battery voltage can be
observed in column
Vdc in the event report.
Station DC Battery Voltage Dips During Circuit Breaker Closing
To generate an event report when the SEL-351A closes the circuit breaker,
make the SEL
OGIC control equation event report generation setting:
ER = /OUT102 + ...
In this example, output contact OUT102 is set to close:
OUT102 = CLOSE (CLOSE is the logic output of Figure 6.1)
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 = /OUT102 + ...) 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 = \SV4T + ...
Timer output SV4T is an example dc voltage element from the bottom of
Figure 8.10. 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 [see Sequential Events Recorder (SER) Report
on page 12.21].
Courtesy of NationalSwitchgear.com
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