GL.4
SEL-751 Relay Instruction Manual Date Code 20170927
Glossary
Fail-Safe—IG
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.
FTP
File transfer protocol.
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-751 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.
GOOSE
IEC 61850 Generic Object Oriented Substation Event. GOOSE objects can
quickly and conveniently transfer status, controls, and measured values among
peers on an IEC 61850 network.
Ground Directional
Element Priority
The order the relay uses to select directional elements to provide ground
directional decisions; relay setting ORDER.
HIF
High-impedance ground fault such as a downed conductor.
IA, IB, IC
Measured A-, B-, and C-phase currents.
ICD File
IEC 61850 IED Capability Description file. An XML file that describes IED
capabilities, including information on logical node and GOOSE support.
IEC 60870-5-103
Standard protocol developed by the IEC Technical Committee of
teleprotection, telecontrol, and telecommunications for electrical engineering
and power system automation. It defines systems used for supervisory control
and data acquisition (SCADA), including details related to communications
between devices.
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.
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