ABB REG670 2.0 IEC Commissioning Manual page 64

Section 6
Calibrating injection based sensitive rotor earth fault protection
58
injection frequency (for example, due to accuracy of the REX060 hardware). Set
manually the actual frequency value measured by ICT in the IED via PST.
The high accuracy of this frequency is essential for proper operation of the protection
under different operating conditions.
Calibrating
The calibration is based on three measurement steps:
1. The injection is made to the faultless generator and the measured complex
impedance is stored.
2. A known resistance is connected between one rotor pole (see Figure 9) and earth.
The injection is made to the generator and the measured complex impedance is
stored.
3. The one rotor pole (see Figure 9) is directly short-circuited to the earth. The
injection is made to the generator and the measured complex impedance is stored.
The sequence of the commissioning calibration measurements is shown in the figure
below.
Step 1
DC
C
rot
AC
REX 061
I
inj
IEC11000205 V1 EN
Figure 9: Different steps at calibration measurements
The sequence of the calibration session follows a scheme shown in the tool.
• Calibration sequence 1: The injection must be activated and the rotor must be left
with no impedance connected. The ICT now makes consecutive measurements
until the statistical error reaches an acceptable value. This is graphically shown in
a diagram. The user stops the sequence by acceptance of the measurement. The
result is stored for later calculations.
• Calibration sequence 2: A known resistor is connected between the rotor winding
and earth. The value of the resistance is the input to ICT. The ICT now makes
consecutive measurements until the statistical error reaches an acceptable value.
This is graphically shown in a diagram. The user stops the sequence by
acceptance of the measurement. The result is stored for later calculations.
• Calibration sequence 3: The generator rotor winding is now directly connected to
earth. The ICT now makes consecutive measurements until the statistical error
reaches an acceptable value. This is graphically shown in a diagram. The user
stops the sequence by acceptance of the measurement. The result is stored for
later calculations.
Step 2
DC
C
rot
AC
REX 061
I
inj
R
Test
Generator protection REG670 2.0 IEC
1MRK502053-UEN B
Step 3
DC
C
rot
AC
REX 061
I
inj
IEC11000205-1-en.vsd
Commissioning manual