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8-18
Breaker Monitor and Metering Functions
Date Code 20010625
SEL-311L Instruction Manual
Timer output SV4T is from the bottom of Figure 8.10. When dc voltage falls below pickup
DCHIP, timer output SV4T drops out (= logical 0), driving the relay to lockout:
79DTL = !SV4T + ... = NOT(SV4T) + ... = NOT(logical 0) + ... = logical 1
View Station DC Battery Voltage
Via Serial Port
See
MET Command (Metering Data)
—Instantaneous Metering in
Section 10: Line Current
Differential Communications and Serial Port Communications and Commands
. The MET
command displays the station dc battery voltage (labeled VDC).
Via Front Panel
The information available via the previously discussed MET serial port command is also
available via the front-panel METER pushbutton. See Figure 11.2 in
Section 11: Front-Panel
Interface
.
Analyze Station DC Battery Voltage
See
Standard 15/30/60-Cycle Event Reports
in
Section 12: Standard Event Reports and SER
.
The station dc battery voltage is displayed in column Vdc in the example event report in Figure
12.4. 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
.
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 5.4). For example, output contact OUT101 is set to trip:
OUT101 = TRIP
When output contact OUT101 closes and energizes the circuit breaker trip coil, any change 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 + ...
When the trip bus is energized, any change in station dc battery voltage can be observed in
column Vdc in the event report.
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