Toshiba GR200 Series - Page 1723

6F2S1914 (0.49)
GRL200 (Soft 033 & 037)
- 1700 -
R
2
: Actual secondary burden [ohms]
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
<Accuracy limit factor of CTs is given>
Table K-2 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
≧ I
Lmax
×18
50
n’ I
n
≧ 3.75 × I
f_rev_max
n’ I
n
≧ I
Lmax
×25
75
n’ I
n
≧ 7.5 × I
f_rev_max
n’ I
n
≧ I
Lmax
×36
100
n’ I
n
≧ 7.5 × I
f_rev_max
n’ I
n
≧ I
Lmax
×46
150
n’ I
n
≧ 7.5 × I
f_rev_max
n’ I
n
≧ I
Lmax
×63
n
RR
RIR
n
ct
ctnVA

+
+
=
2
2
/
'
(K-1)
n’ : Equivalent accuracy limit factor defined by the equation above.
I
n
: Rated current at CT secondary
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
Note : The values in the table are based on the following assumption.
- 100% DC component is superimposed.
- Only one CT is saturated.
- No remnance flux is assumed.