x/EN SG/Na7
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MiCOM P74
Symbols Explanation
CTRL. Abbreviation of “Control”:
As used for the Control Inputs function.
CTS Current transformer supervision:
To detect CT input failure.
CU
Abbreviation of “Central Unit” (P741)
CZ Abbreviation of “Check Zone”:
Zone taking into account only the feeders.
DDB Digital data bus within the programmable scheme logic:
A logic point that has a zero or 1 status. DDB signals are mapped in logic to customize
the relay’s operation.
DEF Directional earth fault protection:
A directionalised ground fault aided scheme.
Df/dt
Rate of change of frequency protection (ROCOF).
Dly
Time delay.
DHP
Dual Homing Protocol
DR
Abbreviation of “Disturbance Record”
DST Daylight Saving Time
DT Abbreviation of “Definite Time”:
An element which always responds with the same constant time delay on operation.
DZ Abbreviation of “Dead Zone”:
Area between a CT and an open breaker or an open isolator.
E/F Earth fault:
Directly equivalent to ground fault.
FLC Full load current:
The nominal rated current for the circuit.
Flt. Abbreviation of “Fault”:
Typically used to indicate faulted phase selection.
FN
Function.
Fwd.
Indicates an element responding to a flow in the “Forward” direction.
F> An overfrequency element:
Could be labelled 81O in ANSI terminology.
F< An underfrequency element:
Could be labelled 81U in ANSI terminology.
GN> Neutral over conductance protection element:
Real component of admittance calculation from neutral current and residual voltage.
Gnd. Abbreviation of “Ground”:
Used in distance settings to identify settings that relate to ground (earth) faults.
GoENa GOOSE Enable
GOOSE Generic Object Oriented Substation Event:
In IEC 61850, a specific definition of a type of generic substation event, for peer-peer
communication.
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