GE P741

P74
x/EN SG/Na7
Symbols and Glossary
(SG) 14
-
4
MiCOM P74
1, P742, P743
SG
Symbols Explanation
ID>2
Minimum pick-up differential phase element for all the zones.
IDCZ>2
Minimum pick-up differential phase element for the Check Zone.
IDMT Inverse definite minimum time:
A characteristic whose trip time depends on the measured input (e.g. current) according
to an inverse-time curve.
IDN>1
Minimum pick-up neutral circuitry fault threshold.
IDN>2
Minimum pick-up differential neutral element for all the zones.
IDNCZ>2
Minimum pick-up differential neutral element for the Check Zone.
IDZ
Minimum pick-up differential neutral element for the Check Zone.
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.
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.
KZN The residual compensation factor:
Ensuring correct reach for ground distance elements.
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.