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
SELV circuit
Safety Extra-Low Voltage circuit type according to
IEC60255-27
SFP
Small form-factor pluggable (abbreviation)
Optical Ethernet port (explanation)
SLM
Serial communication module.
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 (SPA), a serial master/
slave protocol for point-to-point and ring 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
1MRK 500 128-UEN B
Section 9
Glossary
650 series 2.2 IEC
91
Operation manual
