Toshiba GRL100-701B Instruction Manual page 57

I 0X : imaginary part of zero-sequence current of the protected line
I 0R : real part of zero-sequence current of the protected line
I omX : imaginary part of zero-sequence current of the parallel line
I omR : real part of zero-sequence current of the parallel line
The zero-sequence compensation factors are applied to the earth fault measuring elements as
shown in the table below
Element Protected line Parallel line
Z1G
Z2G
Z3G
ZRG
Z4G
−: Compensation is not provided.
The zero-sequence compensation of the parallel line is controlled by the ZPCC (Zero-sequence
Current Compensation) element.
When an earth fault occurs on the protected line, the ZPCC operates and parallel line
compensation is performed to prevent underreach caused by the mutual zero-sequence current of
the parallel line.
When an earth fault on the parallel line occurs, the ZPCC does not operate and the compensation
of parallel line is not performed to prevent overreach. The operating condition of the ZPCC is as
follows:
3I 0 / 3I om ≥ 0.8
Charging current compensation
When distance protection is applied to underground cables or long-distance overhead lines, the
effect of charging current cannot be ignored. It appears as a distance measurement error in the
fault.
To suppress the effect of the charging current and maintain the highly accurate distance
measurement capability, the distance protection of GRL100 has a charging current compensation
function.
The compensation is recommended if the minimum fault current can be less than three times the
charging current.
The setting value of ZIC should be the charging current at the rated voltage Vn.
Element Range
I 0 '
P
I 1 , I 2 , I o
V a
Z 1 , Z 2 , Z o
Figure 2.3.1.13 Earth Fault Compensation
Krs, Kxs Krm, Kxm
Krs, Kxs Krm, Kxm
− −
− −
− −
Step Default
 56 
6 F 2 S 0 8 5 0
Z om
F
Remarks