ABB COM600 series User's & Technical Manual page 32

32
COM600 series 5.1
Substation Analytics Technical Manual
Figure 4.3-29 Equivalent diagram of the protected feeder. RL0F = Ph leakage Ris.
The determination of the Ph capacitive React setting can be based either on network
data or measurement.
If the total phase-to-earth capacitance (including all branches) per phase C0F of the
protected feeder is known, the setting value can be calculated.
Figure 4.3-30 (Equation 19)
In case of unearthed network, if the earth-fault current of the protected feeder Ief is
known, the corresponding phase-to-earth capacitance per phase can be calculated.
Figure 4.3-31 (Equation 20)
Ux phase-to-earth voltage
SCEFRFLO can also determine the value for the Ph capacitive React setting by measure-
ments. The calculation of the value of Ph capacitive React setting is accomplished by
conducting an earth-fault test outside the protected feeder during commissioning, for
example at the substation busbar. The calculated value of the Ph capacitive React setting
is obtained from the XC0F_CALC output. This value must be manually entered for the
Ph capacitive React setting.
The calculated value matches the current switching state of
the feeder and if the switching state of the protected feeder
1MRS758734
equivalent_diagram_protected_feeder.png
equation_19.png
equation_20.png