ABB Relion Technical Manual page 321

1MRK 502 048-UUS A
Technical manual
+ ³
V V Beta V
3T 3N
3N
EQUATION2359-ANSI V1 EN
V , and V are third harmonic phasors with real and imaginary parts. The factor Beta
3N 3T
must be set not to risk operation under non-faulted conditions.
The voltage V is measured via a voltage transformer between the generator neutral point
3N
and ground. The voltage V
defines how the protection function is fed from voltage transformers at the high voltage
side of the generator. If V
function is blocked. The choices of TVoltType are:
NoVoltage: There is no voltage measured from the generator terminal side. This can be the
case when there are only phase-to-phase voltage transformers available at the generator
terminal side. In this case the protection will operate as a simple neutral point 3
undervoltage protection, which must be blocked externally during generator start-up and
shut-down.
ResidualVoltage: The function is fed from a broken delta connection of the phase to
ground connected voltage transformers at the generator terminal side,
V =(1/3)*V_Broken_Delta.
3T
AllThreePhases: The function is fed from the three phase to ground connected voltage
transformers at the generator terminal side. The 3
the IED, V =(1/3)*(V3A+V3B+V3C).
3T
PhaseA, PhaseB, or PhaseC: The function is fed from one phase voltage transformer only.
rd
The 3 harmonic zero sequence voltage is assumed to be equal to any of the phase
voltages, as the third harmonic voltage is of zero sequence type, V
A simplified block diagram describing the stator ground fault protection function shown
in figure 145.
can be measured in different ways. The setting TVoltType
3T
is lower than the set level VT3BlkLevel, STEFPHIZ (59THD)
3T
rd
Section 9
Voltage protection
harmonic voltage V is calculated in
3T
=V3x (x= AB or C.
3T
(Equation 94)
rd
harmonic
315