ABB REG650 ANSI, Technical Manual

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Table 181: STEFPHIZ Non group settings (basic)
Name Values (Range) Unit Step Default Description
GlobalBaseSel 1 - 6 - 1 1 Selection of one of the Global Base Value
groups
TVoltType NoVoltage
ResidualVoltage
AllThreePhases
PhaseL1
PhaseL2
PhaseL3
- - ResidualVoltage Used connection type for gen. terminal
voltage transformer
9.5.6 Monitored data
Table 182: STEFPHIZ Monitored data
Name Type Values (Range) Unit Description
UT3 REAL - kV Mag. of 3rd harm. voltage
at generator terminal side
UN3 REAL - kV Mag. of 3rd harm. voltage
at generator neutral side
E3 REAL - kV Total induced stator 3rd
harmonic voltage
ANGLE REAL - deg Angle between 3rd
harmonic votage phasors
DU3 REAL - kV Diff. between 3rd harm.
volt. at both sides of gen.
BU3 REAL - kV Bias voltage, a part of
UN3
UN REAL - kV Fund. frequency voltage
at generator neutral
9.5.7 Operation principle
The protection is a combination of the 95% fundamental frequency earth fault
protection and the100% Stator earth fault protection, 3
rd
harmonic based,
(STEFPHIZ). The 3
rd
harmonic based 100% stator earth fault protection is using the
3
rd
harmonic voltage generated by the generator itself. To assure reliable function of
the protection it is necessary that the 3
rd
harmonic voltage generation is at least 0.8 V
RMS on VT secondary side.
The 3
rd
harmonic voltage generated by the generator has the same phase angle in the
three phases. It has the characteristic of a zero sequence component. If the generator
is connected to the power system via a block transformer that cannot transform zero
sequence voltages between the voltage levels, the 3
rd
harmonic voltage, that is U
3N
and U
3T
in fig 144 , in the generator system is not influenced by the external power
system. At normal operation the generator third harmonic voltage characteristic can
be described as in figure
144 .
Section 9
1MRK 502 048-UEN A
Voltage protection
288
Technical manual