Date Code 20080918 Instruction Manual SEL-749M Relay
Section 9
Analyzing Events
Instructi on Manual
Overview
The SEL-749M Relay provides several tools (listed below) to analyze the
cause of relay operations. Use these tools to help diagnose the cause of the
relay operation and more quickly restore the protected motor to service.
➤ Event Reporting
➢ Event Summary Reports
➢ Event History Reports
➢ Event Reports
➤ Sequential Events Recorder Report
Resolution: 1 ms
Accuracy: ±1/4 cycle
All reports are stored in nonvolatile memory, ensuring that a loss of power to
the SEL-749M will not result in lost data.
Event Reporting
Analyze events with the following event reporting functions:
➤ Event Summaries—Enable automatic messaging to allow the
relay to send event summaries out a serial port when port
setting AUTO := Y. A summary provides a quick overview of
an event. The summaries may also be retrieved by using the
SUMMARY command.
➤ Event History—The relay keeps an index of stored nonvolatile
event reports. Use the HISTORY command to obtain this
index. The index includes some of the event summary
information so that the appropriate event report can be
identified and retrieved.
➤ Event Reports—These detailed reports are stored in nonvolatile
memory for later retrieval and detailed analysis.
Each time an event occurs a new summary, history record, and report are
created. Event report information includes:
➤ Date and time of the event
➤ Individual sample analog inputs (currents and voltages)
➤ Digital states of selected Relay Word bits (listed in Table G.1
on page G.1)
Courtesy of NationalSwitchgear.com
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