GL.4
SEL-400 Series Relays Instruction Manual Date Code 20171006
Glossary
Axion—Busbar
Axion
Another term for the SEL-2240. The Axion is an integrated, modular input/
output and control solution suited for utility and industrial applications. In TiDL
systems, it is used for remote data acquisition and control.
Bandpass Filter
A filter that passes frequencies within a certain range and blocks all frequencies
outside this range.
Bay
Primary plant including disconnects, circuit breaker, CTs, PTs, power
transformer, etc.
Bay Control
Front-panel control (open and close) of the transformer circuit breakers and
disconnects (isolators).
Best Choice Ground
Directional Element 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.
Breaker Differential
Differential zone of protection configured exclusively across the tie breaker; the
breaker differential protects only the area between the two tie-breaker CTs.
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 because of transport flow control constraints or
loss of connection. Buffered reporting provides sequence-of-events (SOE)
functionality.
Busbar
Electrical junction of two or more primary circuits. For a single busbar, there
could be multiple bus-zones; there can be more bus-zones than busbars, but not
more busbars than bus-zones.
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