Resistance for phase-to-ground faults
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
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.
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.
TNC connector
Threaded Neill-Concelman, a threaded constant impedance version of a
BNC connector
TPZ, TPY, TPX, TPS
Current transformer class according to IEC
UMT
User management tool
1MRK 511 244-UUS A
Section 4
Glossary
DNP, 650 series
49
Point list manual
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