ABB Relion 670 series, Technical Reference Manual, Page: 1226 / 1232

MVB Multifunction vehicle bus. Standardized serial bus originally
developed for use in trains.
NCC National Control Centre
NUM Numerical module
OCO cycle Open-close-open cycle
OCP Overcurrent protection
OEM Optical ethernet module
OLTC On-load tap changer
OV Over-voltage
Overreach A term used to describe how the relay behaves during a fault
condition. For example, a distance relay is overreaching when
the impedance presented to it is smaller than the apparent
impedance to the fault applied to the balance point, that is, the
set reach. The relay “sees” the fault but perhaps it should not
have seen it.
PCI Peripheral component interconnect, a local data bus
PCM Pulse code modulation
PCM600 Protection and control IED manager
PC-MIP Mezzanine card standard
PMC PCI Mezzanine card
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
PSM Power supply module
PST Parameter setting tool within PCM600
PT ratio Potential transformer or voltage transformer ratio
PUTT Permissive underreach transfer trip
RASC Synchrocheck relay, COMBIFLEX
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
Section 23
1MRK505222-UUS C
Glossary
1220
Technical reference manual