ABB RELION REG670 Commissioning Manual page 61

1MRK 502 067-UEN B
GUID-3C7F0567-2367-46E4-9606-FCFC7408DAA0 V1 EN-US
Figure 12:
5. Connect a calibration resistance between one pole of the field winding and ground; the
value of the calibration resistance can be calculated as the impedance to ground of the
rotor:
R
IECEQUATION17027 V2 EN-US
where,
f
inj
C
rot
If the capacitance to ground of the rotor is unknown, a calibration resistance with
tentative value equal to 5000 Ω can be used. This tentative value shall be assessed after
the calibration procedure is completed.
In order to perform the assessment, the first reference impedance, which is calculated
during the tentative calibration, is assumed as an evaluation of the rotor impedance to
ground:
Z
rot
IECEQUATION17028 V3 EN-US
The assessment of the calibration is positive if:
0
IECEQUATION17029 V2 EN-US
The typical higher limit x can be in range between 1% and 5%. If the assessment is
negative, the calibration shall be repeated with a calibration resistance close to the
absolute value of the estimated rotor impedance to ground.
6. Type the value in ohm of the calibration resistance in the real part of the Connected
impedance field and type 0 in the imaginary part field.
This informs the ICT that we have connected a pure resistive impedance that has a value
equal to the typed one.
7. In the ICT toolbar, select the Start reading values from IED button.
The ICT performs consecutive measurements until the statistical error reaches an
acceptable value. This is graphically shown in a diagram.
Commissioning manual
ICT calibration tab 1 including the stability region indicator bar
1
@ @
Z
p
× × ×
cal rot
2 f C
inj
is the frequency of the signal injected by REX60
is the total capacitance to ground of the rotor winding

 
2 2 2
Re f R 1 Re f X 1
Re fR 1 Re fX 1
-
Z R
< £
rot cal
x
Z
rot
Calibrating injection based sensitive rotor earth fault protection
rot
Stability region
indicator bar
IEC11000047-1-en.vsd
Section 6
55