GL.4
SEL-421 Relay Date Code 20090715
Glossary
Bandpass Filter—CID
MMS is the interactive MMS Object Explorer for browser-like access to
IEC 61850 / UCA2 and MMS device objects.
Bandpass Filter
A filter that passes frequencies within a certain range and blocks all
frequencies outside this range.
Best Choice Ground
Directional Supervision™
logic
An SEL logic that determines the directional element that the relay uses for
ground faults.
Bit Label
The identifier for a particular bit.
Bit Value
Logical 0 or logical 1.
Block Trip Extension
Continuing the blocking signal at the receiving relay by delaying the dropout
of Relay Word bit BT.
Blocking Signal Extension
The blocking signal for the DCB (directional comparison blocking) trip
scheme is extended by a time delay on dropout timer to prevent unwanted
tripping following current reversals.
Bolted Fault
A fault with essentially zero impedance or resistance between the shorted
conductors.
Boolean Logic Statements
Statements consisting of variables that behave according to Boolean logic
operators such as AND, NOT, and OR.
Breaker Auxiliary Contact
An electrical contact associated with a circuit breaker that opens or closes to
indicate the breaker position. A form-a breaker auxiliary contact (ANSI
Standard Device Number 52A) closes when the breaker is closed and opens
when the breaker is open. A form-b breaker auxiliary contact (ANSI Standard
Device Number 52B) opens when the breaker is closed and closes when the
breaker is open.
Breaker-and-a-half
Configuration
A switching station arrangement of three circuit breakers per two circuits; the
two circuits share one of the circuit breakers.
Buffered Report
IEC 61850 IEDs can issue buffered reports of internal events (caused by
trigger options data-change, quality-change, and data-update). These event
reports can be sent immediately or buffered (to some practical limit) for
transmission, such that values of data are not lost due to transport flow control
constraints or loss of connection. Buffered reporting provides sequence-of-
events (SOE) functionality.
C37.118
IEEE C37.118, Standard for Synchrophasors for Power Systems
Category
A collection of similar relay settings.
CCVT
Coupling-capacitor voltage transformer that uses a capacitive voltage divider
to reduce transmission voltage to a level safe for metering and relaying
devices. See CVT.
Checksum
A method for checking the accuracy of data transmission involving
summation of a group of digits and comparison of this sum to a previously
calculated value.
CID
Checksum identification of the firmware.
Courtesy of NationalSwitchgear.com
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