GL.3
Date Code 20081022 Instruction Manual SEL-787 Relay
Glossary
Event Report–LED
Event Report
A text-based collection of data stored by the relay in response to a triggering
condition, such as a fault or command. The data show relay measurements
before and after the trigger, in addition to the states of protection elements,
relay inputs, and relay outputs each processing interval. After an electrical
system fault, use event reports to analyze relay and system performance.
Event Summary
A shortened version of stored event reports. An event summary includes items
such as event date and time, event type, fault voltages, currents, etc. The relay
sends an event report summary (if auto messaging is enabled) to the relay
serial port a few seconds after an event.
Fail-Safe
Refers to an output contact that is energized during normal relay operation and
de-energized when relay power is removed or if the relay fails.
Fast Meter, Fast Operate
Binary serial port commands that the relay recognizes at the relay front-and
rear-panel EIA-232 serial ports. These commands and the responses from the
relay make relay data collection by a communications processor faster and
more efficient than transfer of the same data through use of formatted ASCII
text commands and responses.
FID
Relay firmware identification string. Lists the relay model, firmware version
and date code, and other information that uniquely identifies the firmware
installed in a particular relay.
Firmware
The nonvolatile program stored in the relay that defines relay operation.
Flash
A type of nonvolatile relay memory used for storing large blocks of
nonvolatile data, such as load profile records.
Fundamental Frequency
The component of the measured electrical signal for which frequency is equal
to the normal electrical system frequency, usually 50 or 60 Hz. Generally used
to differentiate between the normal system frequency and any harmonic
frequencies present.
Fundamental Meter
Type of meter data presented by the SEL-787 that includes the present values
measured at the relay ac inputs. The word “Fundamental” is used to indicate
that the values are Fundamental Frequency values and do not include
harmonics.
IA, IB, IC
Measured A-, B-, and C-phase currents.
IEC 61850
Standard protocol for real-time exchange of data between databases in multi-
vendor devices.
IG
Residual current, calculated from the sum of the phase currents. In normal,
balanced operation, this current is very small or zero. When a ground fault
occurs, this current can be large.
IN
Neutral current measured by the relay IN input. The IN input is typically
connected to the secondary winding of a window-CT for ground fault
detection on resistance-grounded systems.
LCD
Abbreviation for Liquid Crystal Display. Used as the relay front-panel
alphanumeric display.
LED
Abbreviation for Light-Emitting Diode. Used as indicator lamps on the relay
front panel.
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