ABB Relion Technical Manual page 774

Section 22
Glossary
768
PT ratio
PUTT
RCA
RISC
RMS value
RS422
RS485
RTC
RTU
SA
SBO
SC
SCL
SCS
SCADA
SCT
SDU
SMA connector
SMT
SMS
SNTP
SOF
SPA
SRY
ST
Starpoint
SVC
Potential transformer or voltage transformer ratio
Permissive underreach transfer trip
Relay characteristic angle
Reduced instruction set computer
Root mean square value
A balanced serial interface for the transmission of digital data in
point-to-point connections
Serial link according to EIA standard RS485
Real-time clock
Remote terminal unit
Substation Automation
Select-before-operate
Switch or push button to close
Short circuit location
Station control system
Supervision, control and data acquisition
System configuration tool according to standard IEC 61850
Service data unit
Subminiature version A, A threaded connector with constant
impedance.
Signal matrix tool within PCM600
Station monitoring system
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.
Status of fault
Strömberg protection acquisition, a serial master/slave protocol
for point-to-point communication
Switch for CB ready condition
Switch or push button to trip
Neutral/Wye point of transformer or generator
Static VAr compensation
1MRK 502 048-UUS A
Technical manual