ABB REG650 Technical Manual page 672

Section 22
Glossary
666
RCA Relay characteristic angle
RFPP Resistance for phase-to-phase faults
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.
1MRK 502 043-UUS B
Technical Manual