Toshiba GRL100-701B Instruction Manual page 55

limited to the BFR∗ setting reach as shown in Figure 2.3.1.11(b).
X
Z2
Z1
BFR1
(a)
The BFL angle can be set to 90 to 135° and is set to 120° as a default. The BRL angle is linked with
the BFL angle.
Figure 2.3.1.12 shows an example of the blinder setting when the minimum load impedance is
Z Lmin and Z' Lmin under the load transmitting and receiving conditions.
75°
Z' Lmin
BRR
When Z4 is used for overreaching command protection ie. POP, UOP and BOP, it is necessary
when setting BRR to take account of the setting of the remote end BFR to ensure coordination.
That is, the BRR is set to a value greater than the set value of the remote end BFR (e.g., 120% of
BFR). This ensures that a reverse fault that causes remote end zone 2 or zone 3 to operate is
detected in local zone R and false tripping is blocked.
Setting of earth fault compensation factor (zero sequence compensation)
In order to correctly measure the positive-sequence impedance to the fault point, the current input
to the earth fault measuring elements is compensated by the residual current (3I 0 ) of the protected
line in the case of a single circuit line and by residual current (3I 0 ) of the protected line and
residual current (3I 0 ') of the parallel line in the case of a double circuit line.
Generally, the following equation is used to compensate the zero-sequence voltage drop in the
case of phase "a".
Z3
R
BFR
BFR2
Figure 2.3.1.11 BFR Reach
X
BFL
θ
30°
Figure 2.3.1.12 Blinder Setting
 54 
X
Z3
Z2
Z1
R
BFR1
BFR2
BFR
(b)
BFR
Load Area
75°
R
Z Lmin
θ
BRL
6 F 2 S 0 8 5 0