GL.3
Date Code 20171006 Instruction Manual SEL-400 Series Relays
Glossary
Anti-Aliasing Filter—AX-S4 MMS
These numbers are frequently used within a suffix letter to further designate their
application. The suffix letters used in this instruction manual include the following:
P Phase Element
G Residual/Ground Element
N Neutral/Ground Element
Q Negative-Sequence (3I2) Element
Anti-Aliasing Filter
A low-pass filter that blocks frequencies too high for the given sampling rate to
accurately reproduce.
Apparent Power, S
Complex power expressed in units of volt-amperes (VA), kilovolt-amperes
(kVA), or megavolt-amperes (MVA). Accounts for both real (P) and reactive (Q)
power dissipated in a circuit: S = P + jQ. This is power at the fundamental
frequency only; no harmonics are included in this quantity.
Arcing Resistance
The resistance in the arc resulting from a power line fault.
ASCII
Abbreviation for American Standard Code for Information Interchange. Defines
a standard set of text characters. The relay uses ASCII text characters to
communicate using front-panel and rear-panel EIA-232 serial ports on the relay
and through virtual serial ports.
ASCII Terminal
A terminal without built-in logic or local processing capability that can only send
and receive information.
Assert
To activate. To fulfill the logic or electrical requirements needed to operate a
device. To set a logic condition to the true state (logical 1) of that condition. To
apply a closed contact to a relay input. To close a normally open output contact.
To open a normally closed output contact.
AT Modem Command Set
Dialing String Standard
The command language standard that Hayes Microcomputer Products, Inc.
developed to control autodial modems from an ASCII terminal (usually EIA-232
connected) or a PC containing software allowing emulation of such a terminal.
Autoconfiguration
The ability to determine relay type, model number, metering capability, port ID,
data rate, passwords, relay elements, and other information that an IED (an
SEL-2020/2030 communications processor) needs to automatically communicate
with relays.
Automatic Messages
Messages including status failure and status warning messages that the relay
generates at the serial ports and displays automatically on the front-panel LCD.
Automatic Reclose
Automatic closing of a circuit breaker after a breaker trip by a protective relay.
Automation Variables
Variables that you include in automation SELOGIC control equations.
Autoreclose-
Drive-to-Lockout
A logical condition that drives the autoreclose function out of service with
respect to a specific circuit breaker.
Autotransformer
A transformer with at least two common windings.
AX-S4 MMS
“Access for MMS” is an IEC 61850, UCA2, and MMS client application
produced by SISCO, Inc., for real-time data integration in Microsoft Windows-
based systems supporting OPC and DDE. Included with AX-S4 MMS is the
interactive MMS Object Explorer for browser-like access to IEC 61850/UCA2
and MMS device objects.
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