Sel 2414 - Glossary

Date Code 20130214 Instruction Manual SEL-2414 Transformer Monitor
Glossary
Instruction Manual
Apparent Power, S
Complex power expressed in units of volt-amps (VA), kilovolt-amps (kVA), or
megavolt-amps (MVA). Accounts for both real (P) and reactive (Q) power dissi-
pated in a circuit: S = P + jQ.
ASCII
Abbreviation for American Standard Code for Information Interchange. Defines
a standard way to communicate text characters between two electronic devices.
The SEL-2414 uses ASCII text characters to communicate using the device
front- and rear-panel EIA-232 serial ports.
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.
Checksum
A numeric identifier of the firmware in the device. Calculated by the result of a
mathematical sum of the device code.
CID File
IEC 61850 Configured IED Description file. XML file that contains the
configuration for a specific IED.
CR_RAM
Abbreviation for Critical RAM. Refers to the area of device Random Access
Memory (RAM) where the device stores mission critical data.
CT
Abbreviation for current transformer.
Data Object
In the IEC 61850 protocol, part of a logical node representing specific
information (status or measurement, for example). From an object-oriented point
of view, a data object is an instance of a data class.
Delta (Open)
A phase-to-phase connection of voltage transformers for electrical measuring
purposes. Typically, two voltage transformers are used with one primary lead of
the first transformer connected to A-phase and the other lead connected to
B-phase. The second voltage transformer is connected to measure the voltage
from B-phase to C-phase. When two transformers are used, this connection is fre-
quently called “Open-Delta.”
Dropout Time
The time measured from the removal of an input signal until the output signal
deasserts. The time can be settable, as in the case of a logic variable timer, or can
be a result of the characteristics of an element algorithm, as in the case of an
overcurrent element dropout time.
Device Word
The collection of device element and logic results. Each element or result is rep-
resented by a unique identifier, known as a Device Word bit.
Device Word Bit
A single device element or logic result that the device updates once each process-
ing interval. A Device Word bit can be equal to either logical 1 or logical 0.
Logical 1 represents a true logic condition, picked up element, or asserted contact
input or contact output. Logical 0 represents a false logic condition, dropped out
element, or deasserted contact input or contact output. You can use Device Word
bits in SEL
OGIC
®
control equations to control event triggering, output contacts,
as well as other functions.