Protective Elements
VG, VX - Voltage Supervision [27A, 27TN/59N, 59A]
Available elements:
VG[1] ,VG[2]
All elements of the voltage supervision of the fourth measuring input are
identically structured.
This protective element can be used to (depending on device planning and setting)
Supervison of the calculated or measured residual voltage. The residual voltage can be calculated only if the
phase voltages (star connection) are connected to the measuring inputs of the device.
Supervision of another (auxiliary) voltage against overvoltage or undervoltage.
The following table shows the application options of the voltage protection element
Applications of the VG/VX-Protection
Module
Setting in
Option
ANSI 59N/G Residual voltage protection
(measured or calculated)
Device Planning menu
Setting: V>
Criterion:
Fundamental/TrueRMS
VG Source:
measured/calculated
ANSI 59A Supervision of an Auxiliary
(additional) Voltage in relation to
Overvoltage.
Device Planning menu
Setting: V>
Within the corresponding
Parameter-Set:
VG Source:measured
Criterion:
Fundamental/TrueRMS
ANSI 27A Supervision of an Auxiliary
(additional) Voltage in relation to
Undervoltage.
Device Planning menu
Setting: V<
Within the corresponding
Parameter-Set:
VG Source:measured
Criterion:
Fundamental/TrueRMS
ANSI 27TN/59N “Vx meas H3”
Stator Ground Fault Protection
Note: This option is available in some
Generator Protection Relays only. In order to
detect 100% Stator Ground faults, a 27TN
element has to be or-connected with a 59N
element within the programmable logic.
Device Planning menu
Setting: V<
Within the corresponding
Parameter-Set:
VX Source:measured
Criterion:
VX meas H3
VX Source:
measured
Measuring Mode
For all protection elements it can be determined, whether the measurement is done on basis of the »
Fundamental«
or if »
TrueRMS« measurement is used.
391
MRU4
DOK-HB-MRU4-2E
