8-18
Breaker Monitor, Metering, and Load Profile Functions
Date Code 20001006
SEL-351 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
Circuit breaker tripping and closing requires station dc battery energy. If the station dc batteries
are having a problem and the station dc battery voltage is declining, the relay should not reclose
after a trip – there might not be enough dc battery energy to trip a second time after a reclose.
View Station DC Battery Voltage
Via Serial Port
See
MET Command (Metering Data)
– Instantaneous Metering in
Section 10: 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 OTHER pushbutton. See Figure 11.3 in
Section 11: Front-Panel Interface
.
Analyze Station DC Battery Voltage
See
Standard 15/30-Cycle Event Reports
in
Section 12: Standard Event Reports, Sag/Swell,
Interruption Report, and SER
. The station dc battery voltage is displayed in column Vdc in the
example event report in Figure 12.2. 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 5.1). For example, output contact OUT1 is set to trip:
OUT1 = TRIP
Anytime output contact OUT1 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 IN7 (monitoring the trip bus) in the SEL
OGIC
Control Equation event report
generation setting:
e.g., ER = /IN7 + ...
Anytime the trip bus is energized, any dip in station dc battery voltage can be observed in column
Vdc in the event report.
Summary of Contents for SEL-351
Page 14: ...Courtesy of NationalSwitchgear com ...
Page 16: ...Courtesy of NationalSwitchgear com ...
Page 40: ...Courtesy of NationalSwitchgear com ...
Page 74: ...Courtesy of NationalSwitchgear com ...
Page 146: ...Courtesy of NationalSwitchgear com ...
Page 186: ...Courtesy of NationalSwitchgear com ...
Page 220: ...Courtesy of NationalSwitchgear com ...
Page 304: ...Courtesy of NationalSwitchgear com ...
Page 340: ...Courtesy of NationalSwitchgear com ...
Page 380: ...Courtesy of NationalSwitchgear com ...
Page 450: ...Courtesy of NationalSwitchgear com ...
Page 506: ...Courtesy of NationalSwitchgear com ...
Page 528: ...Courtesy of NationalSwitchgear com ...
Page 534: ...Courtesy of NationalSwitchgear com ...
Page 536: ...Courtesy of NationalSwitchgear com ...
Page 550: ...Courtesy of NationalSwitchgear com ...
Page 562: ...Courtesy of NationalSwitchgear com ...
Page 570: ...Courtesy of NationalSwitchgear com ...
Page 584: ...Courtesy of NationalSwitchgear com ...
Page 602: ...Courtesy of NationalSwitchgear com ...