Toshiba GRL100-701B Instruction Manual page 406

Max{I + I
Lmax fmin
I : Minimum fault current
fmin
I : Maximum out-flowing fault current for the special condition
fmaxout
<Accuracy limit factor of CTs is given>
Td [ms]
35
50
75
100
150
Td [ms]
35
50
75
100
150
R
=
VA
n '
R
n' : Equivalent accuracy limit factor defined by the equation above.
I : Secondary rated current
n
R : Rated secondary burden [VA]
VA
R : Secondary CT resistance [ohms]
ct
R : Actual secondary burden [ohms]
2
n : Rated accuracy limit factor
I : Maximum secondary fault current
fmax
I : Maximum secondary fault current at the zone 1 reach point
f_z1_max
I : Maximum secondary fault current for a close-up reverse fault
f_rev_max
I : Maximum secondary load current
Lmax
Max{I + I
Lmax fmin
I : Minimum fault current
fmin
I : Maximum out-flowing fault current for the special condition
fmaxout
CASE 2. The case with the distance protection applied as a back-up protection with time delay
Similarly to the previous case, the condition shown in Table K-3 and Table K-4 should be
replaced by that in Table K-7 and Table K-8 respectively for "CASE 2".
/2, I }: The larger of (I
fmaxout
Table K-6 CT Requirement defined by n'
Requirement 1
n' I ≧ 3.75 × I
n fmax
n' I ≧ 3.75 × I
n fmax
n' I 5 × I
≧
n fmax
n' I 5 × I
≧
n fmax
n' I ≧ 10 × I
n fmax
Requirement 3
n' I ≧ 2.5 × I
n f_rev_max
n' I ≧ 3.75 × I
n f_rev_max
n' I ≧ 7.5 × I
n f_rev_max
n' I ≧ 7.5 × I
n f_rev_max
n' I ≧ 7.5 × I
n f_rev_max
+
2
/ I R
⋅
n ct
n
+
R
2 ct
/2, I }: The larger of (I
fmaxout
 405 
+ I /2) and I
Lmax fmin fmaxout
Requirement 2
n' I ≧ 7.5 × I
n f_z1_max
n' I ≧ 8.75 × I
n f_z1_max
n' I ≧ 10 × I
n f_z1_max
n' I ≧ 10 × I
n f_z1_max
n' I ≧ 10 × I
n f_z1_max
Requirement 4
n' I >
Max{I + I /2, I }
n Lmax fmin fmaxout
n' I >
Max{I + I /2, I }
n Lmax
fmin fmaxout
n' I >
Max{I + I /2, I }
n Lmax
fmin fmaxout
n' I >
Max{I + I /2, I }
n Lmax
fmin fmaxout
n' I >
Max{I + I /2, I }
n Lmax
fmin fmaxout
(K-1)
+ I /2) and I
Lmax fmin fmaxout
6 F 2 S 0 8 5 0
×18
×25
×36
×46
×63