GE P444

P
44x/EN SG/ Hb6
Symbols and Glossary
(SG) 1
3-6 MiCO
M P40 Agile P442, P444
Symbols Explanation
IED Intelligent Electronic Device:
For example a MiCOM relay
In The rated nominal current of the relay:
Software selectable as 1 amp or 5 amps to match the line CT input.
IN Neutral current, or residual current:
This results from an internal summation of the three measured phase currents.
IN> A neutral (residual) overcurrent element:
Detects earth/ground faults.
IN>1 First stage of ground overcurrent protection:
Could be labelled 51N-1 in ANSI terminology.
IN>2 Second stage of ground overcurrent protection:
Could be labelled 51N-2 in ANSI terminology.
IN>BB Minimum pick-up neutral threshold for the local trip order confirmation.
IN>DZ Minimum pick-up neutral threshold for the Dead Zone protection.
Inh An inhibit signal.
Inst. An element with “instantaneous” operation:
i.e. having no deliberate time delay.
IRIG-B IRIG-B Standard (Inter-Range Instrumentation Group)
ISEF> Sensitive earth fault overcurrent element.
K1 Slope of the phase circuitry fault function.
K2 Slope of the differential phase element for all the zones.
KCZ Slope of the differential phase element for the Check Zone.
KN1 Slope of the neutral circuitry fault function.
KN2 Slope of the differential neutral element for all the zones.
KNCZ Slope of the differential neutral element for the Check Zone.
KZ
Residual compensation factor: Ensuring correct reach for ground distance elements. kZ1 (for Z1
and Zone X), kZ2 (for zone 2), kZ3/Z4 (shared by zones 3 and 4), kZp (Zone P), ZQ (for zone
Q).
LCD Liquid crystal display:
The front-panel text display on the relay.
LD Abbreviation of “Level Detector”:
An element responding to a current or voltage below its set threshold.
LED Light emitting diode:
Bicolour: Red/black or green/black or orange/black indicator on the relay front-panel.
Tricolour: Red/orange/green/black indicator on the relay front-panel.
LN
Logical Nodes
Measured voltages and currents converted into digital sampled values and grouped (used with
Ethernet NCIT board)
MCB A “miniature circuit breaker”:
Used instead of a fuse to protect VT secondary circuits.
MICS Model Implementation Conformance Specification:
Defines the IEC 61850 data model implemented in an IED.
MMS Manufacturing Message Specification:
A protocol used to transport the data of IEC 61850 across an Ethernet network.
N Indication of “Neutral” involvement in a fault:
i.e. a ground (earth) fault.
N/A Not applicable.
N/C A normally closed or “break” contact:
Often called a “form B” contact.