ABB REC670 Operator's Manual page 112

Section 15
Glossary
106
RCA Relay characteristic angle
REVAL Evaluation software
RFPP Resistance for phase-to-phase faults
RFPE Resistance for phase-to-earth 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
SC Switch or push-button to close
SCS Station control system
SCT System configuration tool according to standard IEC 61850
SLM Serial communication module. Used for SPA/LON/IEC
communication.
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.
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 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 511 188-UEN C
Operator's manual