ABB REG670 - Page 74

Stability region
indicator bar
IEC11000047-1-en.vsd
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:
1
2
cal rot
inj rot
RZ
fC
π
==
⋅⋅⋅
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:
Re1
rot
Z fZ
≈
IECEQUATION17028 V1 EN-US
The assessment of the calibration is positive if:
rot cal
rot
ZR
x
Z
−
≤
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.
Section 6 1MRK 502 073-UUS A
Calibrating injection based sensitive rotor earth fault protection
68 Generator protection REG670 2.2 ANSI and Injection equipment REX060, REX061, REX062
Commissioning manual