10.2
SEL-751 Relay Instruction Manual Date Code 20170927
Analyzing Events
Event Reporting
➤ Event summary, including the front-panel target states at the
time of tripping, fault type, and fault location.
➤ Group, Logic, Global, and Report settings (that were in service
when the event was recorded)
Compressed Event
Reports
The SEL-751 provides Compressed ASCII and COMTRADE event reports to
facilitate event report storage and display. SEL communications processors
and the
ACSELERATOR Analytic Assistant SEL-5601 Software take advantage
of the Compressed ASCII and COMTRADE formats. Use the CHIS
command to display Compressed ASCII event history information. Use the
CSUM command to display Compressed ASCII event summary information.
Use the CEVENT command to display Compressed ASCII event reports.
For accurate event report analysis, use the Compressed Event report with raw
(unfiltered) data (CEV R command). The regular ASCII Event report is useful
for a quick check. See Table C.2 for further information.
Compressed ASCII Event Reports contain all of the Relay Word bits.
Additionally, the SEL-751 Compressed Event (CEV command) report
includes analog channels for the % arc-flash sensor light values and frequency
measurements that are not available in the regular ASCII Event (EVE
command) report.
Sequential Events
Recorder (SER)
The SER report captures digital element state changes over time. Settings
allow as many as 96 Relay Word bits to be monitored, in addition to the
automatically generated triggers for relay power up, settings changes, and
active setting group changes. State changes are time-tagged to the nearest
millisecond. SER information is stored when state changes occur.
SER report data are useful in commissioning tests and during operation for
system monitoring and control.
Event Reporting
Length
The SEL-751 provides selectable event report length (LER) and prefault
length (PRE). Event report length is either 15, 64, or 180 cycles. Prefault
length is 1–10 cycles for LER = 15, 1–59 cycles for LER = 64, and 1–175
cycles for LER = 180. Prefault length is the first part of the total event report
length and precedes the event report triggering point. Changing the PRE
setting has no effect on the stored reports. The relay stores as many as six of
the most recent 180-cycle, seventeen of the most recent 64-cycle, or as many
as seventy of the most recent 15-cycle event reports in nonvolatile memory.
Refer to the SET
R command in SET Command (Change Settings) on
page 7.47 and Report Settings (SET R Command) on page SET.66.
Triggering
The SEL-751 triggers (generates) an event report when any of the following occur:
➤ Relay Word bit TRIP asserts
➤ Programmable SELOGIC control equation setting ER asserts (in
Report settings)
➤ TRI (Trigger Event Reports) serial port command executes
IMPORTANT: Changing the LER
setting clears all events in memory.
Be sure to save critical event data
prior to changing the LER setting.
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