Toshiba GRL100-701B Instruction Manual page 157

Fault location using the only local end data
The setting items necessary for the fault location and their setting ranges are shown in the table
below. The settings of R 0m and X 0m are only required for the double circuit lines. The reactance
and resistance values are input in expressions on the secondary side of CT and VT.
When there are great variations in the impedance of each phase, equation (10) is used to find the
positive sequence impedance, zero sequence impedance and zero sequence mutual impedance,
while equation (11) is used to find imbalance compensation factors K ab to K a .
When variations in impedance of each phase can be ignored, the imbalance compensation factor is
set to 100%.
Z 1 = {(Z aa + Z bb + Z cc )
Z 0 = {(Z aa + Z bb + Z cc ) + 2(Z ab + Z bc + Z ca )}/3
Z 0m = (Z am + Z bm + Z cm )/3
K ab = {(Z aa + Z bb )/2
K bc = {(Z bb + Z cc )/2
K ca = {(Z cc + Z aa )/2
K a = {Z aa − (Z ab + Z ca )/2}/Z 1
K b = {Z bb − (Z bc + Z ab )/2}/Z 1
−
K c = {Z cc (Z ca + Z ab )/2}/Z 1
The scheme switch [FL-Z0B] is used when zero sequence compensation of the parallel line is not
performed in double circuit line.
The switch [FL-Z0B] is set to "OFF" when the current input to the earth fault measuring element is
compensated by residual current of the parallel line. When not, the switch [FL-Z0B] is set to "ON"
and Z0B-L, Z0B-R, R 0m and X 0m are set.
Z0B-L = zero sequence back source impedance at local terminal
Z0B-R = zero sequence back source impedance at remote terminal
In double circuit line, however, it is recommended that the current input compensated by residual
current of the parallel line is used in order for the earth fault measuring element to correctly
measure the impedance.
In the case of single circuit line, the switch [FL-Z0B] is set to "OFF".
−
(Z ab + Z bc + Z ca )}/3
−
Z ab }/Z 1
− Z bc }/Z 1
−
Z ca }/Z 1
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6 F 2 S 0 8 5 0
(10)
(11)