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Glossary Chapter 14
Glossary
IP 40 Ingression Protection, According to IEC standard, level 40
IP 54 Ingression Protection, According to IEC standard, level 54
ITU International Telecommunications Union
LAN Local Area Network
LIB 520 High voltage software module
LCD Liquid Crystal Display
LDCM Line Differential Communication Module
LDD Local detection device
LED Light Emitting Diode
LNT LION Network Tool
LON Local Operating Network
MCB Miniature Circuit Breaker
MCM Mezzanine Carrier Module
MIM Milli-ampere module
MPM Main Processing Module
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
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 over-reaching when the impedance pre-
sented to it is smaller than the apparent impedance to the fault applied
to the balance point, i.e. the set reach. The relay “sees” the fault but per-
haps it should not have seen it.
PCI Peripheral Component Interconnect, a local data bus
PCM Pulse code modulation
PCM600 Protection and Control IED 600 Manager
PISA Process interface for sensors & actuators
POTT Permissive overeach 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
PT ratio Potential transformer or voltage transformer ratio
PUTT Permissive underreach transfer trip
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