9.6
SEL-787 Relay Instruction Manual Date Code 20081022
Analyzing Events
Event Reporting
Use the front-panel MAIN > Events > Display menu to display event history
data on the SEL-787 front-panel display.
Use the
ACSELERATOR QuickSet software to retrieve the relay event history.
View the Relay Event History dialog box via the Analysis > Get Event Files
menu.
Clearing
Use the HIS C command to clear or reset history data from Access Levels 1
and higher. Clear/reset history data at any communications port. This will
clear all event summaries, history records, and reports.
Event Reports
The latest event reports are stored in nonvolatile memory. The 787 relay
captures the following types of data:
➤ Analog values
➤ Digital states of the protection and control elements, plus status
of digital output and input states
➤ Event Summary
➤ Settings in service at the time of event trigger, consisting of
Group, Logic, Global, and Report settings classes
The SEL-787 supports the following three separate event report types:
➤ Standard Analog Event Report (EVE command)
➤ Digital Event Report (EVE D command)
➤ Differential Event Report (EVE DIFz command, where z = 1,
2, or 3 for the three 87 elements)
Analog Event Reports (EVE Command)
The Analog Event Report includes:
➤ Analog values of Winding 1 and 2 currents; IAW, IBW, ICW,
IGW, (IGW only if voltage card is not used), neutral current IN
(if available), voltages and frequency (if voltage card is used)
➤ Digital states of the base model digital inputs (2) and digital
outputs (3)
➤ Event Summary
➤ Relay Settings
Filtered and Unfiltered Analog Event Reports
The SEL-787 samples the power system measurands (ac voltage and ac
current) 16 times per power system cycle. A digital filter extracts the
fundamental frequency component of the measurands. The relay operates on
the filtered values and reports these values in the standard, filtered event
report.
To view the raw inputs to the relay, select the unfiltered event report using the
EVE R command. Use the unfiltered event reports to observe power system
conditions:
➤ Power system transients on current and voltage channels
➤ Decaying dc offset during fault conditions on current channels
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