ABB RELION RET670, Commissioning Manual, Page: 323 / 328

POR Permissive overreach
POTT Permissive overreach transfer trip
Process bus Bus or LAN used at the process level, that is, in near proximity
to the measured and/or controlled components
PRP Parallel redundancy protocol
PSM Power supply module
PST Parameter setting tool within PCM600
PTP Precision time protocol
PT ratio Potential transformer or voltage transformer ratio
PUTT Permissive underreach transfer trip
RASC Synchrocheck relay, COMBIFLEX
RCA Relay characteristic angle
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
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
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.
1MRK 504 165-UUS -
Section 16
Glossary
Transformer protection RET670 2.2 ANSI 317
Commissioning manual