ABB REQ650 Applications Manual page 330

Section 18
Glossary
324
NOF
NUM
OCO cycle
OCP
OLTC
OTEV
OV
Overreach
PCI
PCM
PCM600
PC-MIP
PMC
POR
POTT
Process bus
PRP
PSM
PST
PTP
PT ratio
PUTT
RASC
RCA
RISC
RMS value
RS422
RS485
RTC
Number of grid faults
Numerical module
Open-close-open cycle
Overcurrent protection
On-load tap changer
Disturbance data recording initiated by other event than
start/pick-up
Overvoltage
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.
Peripheral component interconnect, a local data bus
Pulse code modulation
Protection and control IED manager
Mezzanine card standard
PCI Mezzanine card
Permissive overreach
Permissive overreach transfer trip
Bus or LAN used at the process level, that is, in near
proximity to the measured and/or controlled components
Parallel redundancy protocol
Power supply module
Parameter setting tool within PCM600
Precision time protocol
Potential transformer or voltage transformer ratio
Permissive underreach transfer trip
Synchrocheck relay, COMBIFLEX
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
1MRK 505 383-UEN A
Breaker protection REQ650 2.2 IEC
Application manual