Monitored Data - ABB Relion Technical Manual

1MRK 502 048-UUS A
9.5.6
9.5.7
Technical manual

Monitored data

Table 182: STEFPHIZ (59THD) Monitored data
Name Type
VT3 REAL
VN3 REAL
E3 REAL
ANGLE REAL
DV3 REAL
BV3 REAL
V_N REAL
Operation principle
The protection is a combination of the 95% fundamental frequency ground fault
protection and the100% Stator ground fault protection, 3
rd
59THD). The 3 harmonic based 100% stator ground fault protection is using the 3
harmonic voltage generated by the generator itself. To assure reliable function of the
protection it is necessary that the 3
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
V in fig 144, in the generator system is not influenced by the external power system. At
3T
normal operation the generator third harmonic voltage characteristic can be described as
in figure 144.
Note that angle between V
Values (Range) Unit
- kV
- kV
- kV
- deg
- kV
- kV
- kV
rd
harmonic voltage generation is at least 0.8 V RMS on
and V is typically close to 180°.
3N 3T
Section 9
Voltage protection
Description
Mag. of 3rd harm. voltage at
generator terminal side
Mag. of 3rd harm. voltage at
generator neutral side
Total induced stator 3rd
harmonic voltage
Angle between 3rd harmonic
votage phasors
Diff. between 3rd harm. volt. at
both sides of gen.
Bias voltage, a part of UN3
Fund. frequency voltage at
generator neutral
rd
harmonic based, (STEFPHIZ,
rd
harmonic voltage, that is V
rd
and
3N
313