SPA Strömberg Protection Acquisition (SPA), a serial master/slave protocol for
point-to-point and ring communication.
SRY Switch for CB ready condition
ST Switch or push button to trip
Starpoint Neutral/Wye point of transformer or generator
SVC Static VAr compensation
TC Trip coil
TCS Trip circuit supervision
TCP Transmission control protocol. The most common transport layer protocol
used on Ethernet and the Internet.
TCP/IP Transmission control protocol over Internet Protocol. The de facto
standard Ethernet protocols incorporated into 4.2BSD Unix. TCP/IP was
developed by DARPA for Internet working and encompasses both network
layer and transport layer protocols. While TCP and IP specify two protocols
at specific protocol layers, TCP/IP is often used to refer to the entire US
Department of Defense protocol suite based upon these, including Telnet,
FTP, UDP and RDP.
TEF Time delayed gound-fault protection function
TLS Transport Layer Security
TM Transmit (disturbance data)
TNC connector Threaded Neill-Concelman, a threaded constant impedance version of a
BNC connector
TP Trip (recorded fault)
TPZ, TPY, TPX, TPS Current transformer class according to IEC
TRM Transformer Module. This module transforms currents and voltages taken
from the process into levels suitable for further signal processing.
TYP Type identification
UMT User management tool
Underreach A term used to describe how the relay behaves during a fault condition. For
example, a distance relay is underreaching when the impedance presented
to it is greater than the apparent impedance to the fault applied to the
balance point, that is, the set reach. The relay does not “see” the fault but
perhaps it should have seen it. See also Overreach.
UTC Coordinated Universal Time. A coordinated time scale, maintained by the
Bureau International des Poids et Mesures (BIPM), which forms the basis of
a coordinated dissemination of standard frequencies and time signals.
UTC is derived from International Atomic Time (TAI) by the addition of a
whole number of "leap seconds" to synchronize it with Universal Time 1
(UT1), thus allowing for the eccentricity of the Earth's orbit, the rotational
axis tilt (23.5 degrees), but still showing the Earth's irregular rotation, on
which UT1 is based. The Coordinated Universal Time is expressed using a
24-hour clock, and uses the Gregorian calendar. It is used for aeroplane and
ship navigation, where it is also sometimes known by the military name,
"Zulu time." "Zulu" in the phonetic alphabet stands for "Z", which stands for
longitude zero.
UV Undervoltage
1MRK 502 066-UUS B Section 27
Glossary
1423
Technical manual
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