P54x/EN SG/La4 Symbols and Glossary
(SG) 14-2
MiCOM P543, P544, P545 & P546
SG
Symbols Explanation
CTx Channel Transmit:
Typically used to indicate a teleprotection signal send.
CVT
Capacitor-coupled Voltage Transformer - equivalent to terminology CCVT.
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 directionalized ground fault aided scheme.
Df/dt
Rate of Change of Frequency
df/dt>1 First stage of df/dt protection
Diff
Differential protection.
Dist
Distance protection.
Dly
Time delay.
DST
Daylight Saving Time
DT Abbreviation of “Definite Time”:
An element which always responds with the same constant time delay on operation.
E/F Earth fault:
Directly equivalent to ground fault.
F<1 First stage of under frequency protection:
Could be labeled 81-U in ANSI terminology.
F>1 First stage of over frequency protection:
Could be labeled 81-O in ANSI terminology.
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.
Gnd. Abbreviation of “Ground”:
Used in distance settings to identify settings that relate to ground (earth) faults.
GPS Abbreviation of “Global Positioning Systems”
GRP. Abbreviation of “Group”:
Typically an alternative setting group.
I
Current.
I
Current raised to a power:
Such as when breaker statistics monitor the square of ruptured current squared
(
power = 2).
I< An undercurrent element:
Responds to current dropout.
I>1 First stage of phase overcurrent protection:
Could be labeled 51-1 in ANSI terminology.
I>2 Second stage of phase overcurrent protection:
Could be labeled 51-2 in ANSI terminology.
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