Toshiba GR200 Series - Page 1728

6F2S1914 (0.49)
GRL200 (Soft 033 & 037)
- 1705 -
<Accuracy limit factor of CTs is given>
Table K-6 CT Requirement defined by n’
Td [ms]
Requirement 1
Requirement 2
35
n’ I
n
≧ 3.75 × I
fmax
n’ I
n
≧ 7.5 × I
f_z1_max
50
n’ I
n
≧ 3.75 × I
fmax
n’ I
n
≧ 8.75 × I
f_z1_max
75
n’ I
n
≧ 5 × I
fmax
n’ I
n
≧ 10 × I
f_z1_max
100
n’ I
n
≧ 5 × I
fmax
n’ I
n
≧ 10 × I
f_z1_max
150
n’ I
n
≧ 10 × I
fmax
n’ I
n
≧ 10 × I
f_z1_max
Td [ms]
Requirement 3
Requirement 4
35
n’ I
n
≧ 2.5 × I
f_rev_max
n’ I
n
> Max{I
Lmax
+ I
fmin
/2, I
fmaxout
}×18
50
n’ I
n
≧ 3.75 × I
f_rev_max
n’ I
n
> Max{I
Lmax
+ I
fmin
/2, I
fmaxout
}×25
75
n’ I
n
≧ 7.5 × I
f_rev_max
n’ I
n
> Max{I
Lmax
+ I
fmin
/2, I
fmaxout
}×36
100
n’ I
n
≧ 7.5 × I
f_rev_max
n’ I
n
> Max{I
Lmax
+ I
fmin
/2, I
fmaxout
}×46
150
n’ I
n
≧ 7.5 × I
f_rev_max
n’ I
n
> Max{I
Lmax
+ I
fmin
/2, I
fmaxout
}×63
n
RR
RIR
n
ct
ctnVA

+
+
=
2
2
/
'
(K-1)
n’ : Equivalent accuracy limit factor defined by the equation above.
I
n
: Secondary rated current
R
VA
: Rated secondary burden [VA]
R
ct
: Secondary CT resistance [ohms]
R
2
: Actual secondary burden [ohms]
n : Rated accuracy limit factor
I
fmax
: Maximum secondary fault current
I
f_z1_max
: Maximum secondary fault current at the zone 1 reach point
I
f_rev_max
: Maximum secondary fault current for a close-up reverse fault
I
Lmax
: Maximum secondary load current
Max{I
Lmax
+ I
fmin
/2, I
fmaxout
}:
The larger of (I
Lmax
+ I
fmin
/2) and I
fmaxout
I
fmin
: Minimum fault current
I
fmaxout
: Maximum out-flowing fault current for the special condition
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”.