Monitored Data; Operation Principle - ABB REG650 Technical Manual

1MRK 502 034-UEN -
8.5.6
8.5.7
Technical Manual

Monitored data

Table 154: STEFPHIZ Monitored data
Name Type
UT3 REAL
UN3 REAL
E3 REAL
ANGLE REAL
DU3 REAL
BU3 REAL
UN REAL

Operation principle

The protection is a combination of the 95% fundamental frequency earth fault
protection and the100% Stator earth fault protection, 3
rd
(STEFPHIZ). The 3 harmonic based 100% stator earth fault protection is using
rd
the 3 harmonic voltage generated by the generator itself. To assure reliable
function of the protection it is necessary that the 3
at least 0.8 V RMS on VT secondary side.
rd
The 3 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
voltage, that is U and U
3N
the external power system. At normal operation the generator third harmonic
voltage characteristic can be described as in figure 127.
Note that angle between U
Values (Range) Unit
-
-
-
-
-
-
-
in fig 127, in the generator system is not influenced by
3T
and U is typically close to 180°.
3N 3T
Section 8
Voltage protection
Description
kV Mag. of 3rd harm.
voltage at generator
terminal side
kV Mag. of 3rd harm.
voltage at generator
neutral side
kV Total induced stator 3rd
harmonic voltage
deg Angle between 3rd
harmonic votage phasors
kV Diff. between 3rd harm.
volt. at both sides of gen.
kV Bias voltage, a part of
UN3
kV Fund. frequency voltage
at generator neutral
rd
harmonic based,
rd
harmonic voltage generation is
rd
harmonic
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