ABB REG670 Commissioning Manual page 70

Section 6
Calibrating injection based sensitive rotor earth fault protection
64
GUID-3C7F0567-2367-46E4-9606-FCFC7408DAA0 V1 EN-US
Figure 11: ICT calibration tab 1 including the stability region indicator bar
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 Z
× × p
cal rot
2
IECEQUATION17027 V1 EN-US
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.
The first reference impedance, which is calculated during the tentative
calibration, is assumed as an evaluation of the rotor impedance to ground:
»
Z Re fZ 1
rot
IECEQUATION17028 V1 EN-US
The assessment of the calibration is positive if:
-
Z R
£
rot cal
x
Z
rot
IECEQUATION17029 V1 EN-US
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.
Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062
1
×
f C
inj rot
1MRK 502 073-UEN A
Stability region
indicator bar
IEC11000047-1-en.vsd
Commissioning manual