GL.12
SEL-421 Relay Date Code 20090715
Glossary
IEC 61850—Load Encroachment
IEC 61850
Internationally standardized method of communications and integration
conceived with the goal of supporting systems of multivendor IEDs networked
together to perform protection, monitoring, automation, metering, and control.
IED
Intelligent electronic device.
IEEE
Institute of Electrical and Electronics Engineers, Inc.
IG
Residual current, calculated from the sum of the phase currents. In normal,
balanced operation, this current is very small or zero.
IGBT
Insulated gate bipolar junction transistor.
Independent Zone Timing
The provision of separate zone timers for phase and ground distance elements.
Infinite Bus
A constant-voltage bus.
Input Conditioning
The establishment of debounce time and assertion level.
Instance
A subdivision of a relay settings class. Group settings have several
subdivisions (Group 1–Group 6), while the Global settings class has one
instance.
Instantaneous Meter
Type of meter data presented by the SEL-421 that includes the present values
measured at the relay ac inputs. The word “Instantaneous” is used to
differentiate these values from the measurements presented by the demand,
thermal, energy, and other meter types.
IP Address
An identifier for a computer or device on a TCP/IP network. Networks using
the TCP/IP protocol route messages based on the IP address of the destination.
The format of an IP address is a 32-bit numeric address written as four
numbers separated by periods. Each number can be zero to 255. For example,
1.160.10.240 could be an IP address.
IRIG-B
A time code input that the relay can use to set the internal relay clock.
Jitter
Time, amplitude, frequency, or phase-related abrupt, spurious variations in
duration, magnitude, or frequency.
L/R
Circuit inductive/resistive ratio.
Latch Bits
Nonvolatile storage locations for binary information.
LED
Light-emitting diode. Used as indicators on the relay front panel.
Left-Side Value
LVALUE. Result storage location of a SELOGIC control equation.
Line Impedance
The phasor sum of resistance and reactance in the form of positive-sequence,
negative-sequence, and zero-sequence impedances of the protected line.
LMD
SEL distributed port switch protocol.
LN Operator
Math SELOGIC control equation operator that provides natural logarithm.
Load Encroachment
The load-encroachment feature allows setting of phase overcurrent elements
and phase distance elements independent of load levels.
Courtesy of NationalSwitchgear.com
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