Toshiba GR200 Series Instruction Manual page 410

Ib, Ic: Line-to-neutral currents when a phase-bc fault arises
Ibc: Line-to-line currents when a phase-bc fault arises (=Ib−Ic)
Vbc: Line-to-line voltages when a phase-bc fault arises (=Vb−Vc)
ILb: Load-current in phase-b before the fault
ILc: Load-current in phase-c before the fault
Iβ': Load-current change before and after the fault (=(Ib−Ic)−(ILb−ILc))
Iβ": Complex conjugate of Iβ'
R1: Resistance component of line impedance1 in positive-sequence
Χ1: Reactance component of line impedance1 in positive-sequence
Kbc: Compensation factor2 for imbalance impedance
L: Line length3 in the kilometer or mile
Im( ): Expression of imaginary part when a value is placed in parentheses
Re( ): Expression of real part when a value is placed in parentheses
• : Symbol of Vector product
Note: For example, user should set the R 1 and the X 1 with settings [FL_1R1] and
1
setting [FL_1X1] respectively, when the impedance of line GJ is considered in
symmetrical components, as shown in Figure 2.32-2. For further information, see
section 2.32.6(iii).
Note: User should set the K ab , K bc and K ca with settings [FL_Kab], [FL_Kbc], and
2
[FL_Kca], when the imbalance impedance is considered. For further information,
see section 2.32.6(vi).
Note: User should set the line length for settings [FL_1line_km] when the length of line
3
GJ is considered and when the unit of length is represented by kilometer, as
shown in Figure 2.32-2. For further information, see section 2.32.6(v).
Compensation for long line
When the line length is beyond 100km, the result of Equation (2.32-16) requires compensation.
Equation (2.32-17) is used to find the compensated distance (χ") with respect to the fault
distance (χ) which is the result of Equation (2.32-16):
where,
k: Propagation constant fixed of the line (0.001����
Calculation principle for earth fault
(ii)
Equations
When we suppose the occurrence of an earth fault in phase-a, the fault distance (χ) is
3
��
2
χ" = �� − �� ×
3
- 387 -
6F2S1914 (0.49)
(2.32-17)
)
−1
GRL200 (Soft 033 & 037)