ABB REG650 Technical Manual page 293

1MRK 502 043-UUS B
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
3N
point and ground. The voltage V
TVoltType defines how the protection function is fed from voltage transformers at the
high voltage side of the generator. If V
STEFPHIZ (59THD) 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
rd
3 harmonic 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
in the IED, V =(1/3)*(V3A+V3B+V3C).
3T
PhaseA, PhaseB, or PhaseC: The function is fed from one phase voltage transformer
rd
only. 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
AB or C.
A simplified block diagram describing the stator ground fault protection function
shown in figure 132.
can be measured in different ways. The setting
3T
is lower than the set level VT3BlkLevel,
3T
rd
harmonic voltage V
Section 9
Voltage protection
(Equation 91)
is calculated
3T
=V3x (x=
3T
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