ABB Relion 670 Series Installation And Commissioning Manual page 114

Section 10
Calibrating injection based sensitive rotor earth fault protection
108
set 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 65) and
earth. The injection is made to the generator and the measured complex
impedance is stored.
3. The one rotor pole (see Figure 65) 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 65: 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
Step 2
DC
C
rot
AC
REX 061
I
inj
R
Test
Installation and commissioning manual
1MRK 502 029-UEN A
Step 3
DC
C
rot
AC
REX 061
I
inj
IEC11000205-1-en.vsd