GE P742

Symbols and Glossary
P74x/EN SG/N
a7
MiCOM P74
1, P742, P743
(SG) 14-
7
SG
Symbols Explanation
V<1 First stage of undervoltage protection:
Could be labelled 27-1 in ANSI terminology.
V<2 Second stage of undervoltage protection:
Could be labelled 27-2 in ANSI terminology.
V>
An overvoltage element.
V>1 First stage of overvoltage protection:
Could be labelled 59-1 in ANSI terminology.
V>2 Second stage of overvoltage protection:
Could be labelled 59-2 in ANSI terminology.
V
0
Zero sequence voltage:
Equals one third of the measured neutral/residual voltage.
V
1
Positive sequence voltage.
V
2
Negative sequence voltage.
V2pol
Negative sequence polarizing voltage.
VA Phase A voltage:
Might be phase L1, red phase. or other, in customer terminology.
VB Phase B voltage:
Might be phase L2, yellow phase. or other, in customer terminology.
VC Phase C voltage:
Might be phase L3, blue phase. or other, in customer terminology.
VCO
Voltage controlled overcurrent element.
Vk
IEC knee point voltage of a current transformer.
Vn The rated nominal voltage of the relay:
To match the line VT input.
VN
Neutral voltage displacement or residual voltage.
VN>1
First stage of residual (neutral) overvoltage protection.
VN>2
Second stage of residual (neutral) overvoltage protection.
Vres.
Neutral voltage displacement or residual voltage.
VT
Voltage transformer.
VTS Voltage transformer supervision:
To detect VT input failure.
Vx An auxiliary supply voltage:
Typically the substation battery voltage used to power the relay.
YN> Neutral overadmittance protection element:
Non-
directional neutral admittance protection calculated from neutral current and
residual voltage.
Z
0
Zero sequence impedance.
Z
1
Positive sequence impedance.
Z
2
Negative sequence impedance.