Schweitzer Engineering Laboratories, Inc.
SEL-787-2, -3, -4 Data Sheet
17
Figure 18
SEL-5078
SYNCHRO
WAV
E
Console Real-Time,
Wide-Area Visualization Tool
Event Reporting and SER
Event reports and the SER simplify post-fault analysis
and improve understanding of simple and complex pro-
tective scheme operations. In response to a user-selected
trigger, the voltage, current, frequency, and element sta-
tus information contained in each event report confirms
relay, scheme, and system performance for every fault.
Decide how much detail is necessary when you request
an event report (e.g., 1/4-cycle or 1/32-cycle resolution,
filtered or raw analog data, respectively).
The relay stores as many as 5 of the most recent
180-cycle event reports, 18 of the most recent 64-cycle
event reports, or 50 of the most recent 15-cycle event
reports in nonvolatile memory. The relay always appends
relay settings to the bottom of each event report.
The following analog data formats are available:
➤
1/4-cycle or 1/32-cycle resolution, filtered or unfil-
tered analog, ASCII or Compressed ASCII reports
➤
1/4-cycle filtered analog, ASCII differential reports
➤
1/32-cycle resolution COMTRADE reports
The relay SER feature stores the latest 1,024 entries. Use
this feature to gain a broad perspective at a glance. An
SER entry helps to monitor input/output change-of-state
occurrences and element pickup/dropout.
Synchronized Measurements
The IRIG-B time-code input synchronizes the SEL-787
internal clock time to within ±1
s of the time-source
input. Convenient sources for this time code are an
SEL-2401 Satellite-Synchronized Clock, an SEL
communications processor, or an SEL RTAC (via Serial
Port 3 on the SEL-787). For time accuracy specifications
for metering, synchrophasors, and events, see
Substation Battery Monitor
The SEL-787 relays that include the enhanced voltage
option with the monitoring package measure and report
the substation battery voltage connected to the VBAT ter-
minals. The relay includes two programmable threshold
comparators and associated logic for alarm and control.
For example, if the battery charger fails, the measured dc
falls below a programmable threshold. The SEL-787
alarms to alert operations personnel before the substation
battery voltage falls to unacceptable levels. Monitor
these thresholds with an SEL communications processor
and trigger messages, telephone calls, or other actions.
The measured dc voltage appears in the meter display
and the Vdc column of the event report. Use the event
report column data to see an oscillographic display of the
battery voltage. This display shows how much the
substation battery voltage drops during trip, close, and
other control operations.
Circuit Breaker Contact Wear
Monitor
Circuit breakers experience mechanical and electrical
wear every time they operate. Intelligent scheduling of
breaker maintenance takes into account the manufac-
turer’s published data of contact wear versus interruption
levels and operation count. With the breaker manufac-
turer’s maintenance curve as input data, the SEL-787
breaker monitor feature compares these input data to the
measured (unfiltered) ac current at the time of a trip and
the number of close-to-open operations.
Every time the breaker trips, the relay integrates the
measured current information. When the result of this
integration exceeds the breaker wear curve threshold
(see
), the relay alarms via output contact,
communications port, or front-panel display. This kind of
information allows timely and economical scheduling of
breaker maintenance.
Figure 19
Breaker Contact Wear Curve and Settings
Through-Fault Monitoring
A through fault is an overcurrent event external to the
differential protection zone. While a through fault is not
kA Interrupted
(Set Point 1)
(Set Point 2)
(Set Point 3)
Breaker Manufacturer's
Maintenance Curve
Close to Open Operations
