ABB RELION 650 SERIES, Applications Manual

Page: 259 / 262

PT ratio Potential transformer or voltage transformer ratio
PUTT Permissive underreach transfer trip
RCA Relay characteristic angle
RISC Reduced instruction set computer
RMS value Root mean square value
RS422 A balanced serial interface for the transmission of digital data in point-to-
point connections
RS485 Serial link according to EIA standard RS485
RTC Real-time clock
RTU Remote terminal unit
SA Substation Automation
SBO Select-before-operate
SC Switch or push button to close
SCL Short circuit location
SCS Station control system
SCADA Supervision, control and data acquisition
SCT System configuration tool according to standard IEC 61850
SDU Service data unit
SMA connector Subminiature version A, A threaded connector with constant impedance.
SMT Signal matrix tool within PCM600
SMS Station monitoring system
SNTP Simple network time protocol – is used to synchronize computer clocks on
local area networks. This reduces the requirement to have accurate
hardware clocks in every embedded system in a network. Each embedded
node can instead synchronize with a remote clock, providing the required
accuracy.
SOF Status of fault
SPA Strömberg protection acquisition, a serial master/slave protocol for point-
to-point 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
1MRK 505 287-UUS B Section 17
Glossary
Busbar protection REB650 253
Application manual
© Copyright 2013 ABB. All rights reserved