Toshiba GR200 Series - Page 1725

6F2S1914 (0.49)
GRL200 (Soft 033 & 037)
- 1702 -
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
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.
Special case
In the case of a 3 terminal-double circuit line configuration, an additional system
condition must be considered. It is possible, under certain circumstances, that when
an internal fault occurs, out-flowing fault current can also be experienced.
In this case, the effect of the out-flowing fault current must be considered when
calculating DIFI1 and DIFI2. For example, the following application can be
considered.
Terminal A
Terminal B
Terminal C
Line 2
Line 1
X
Y
Y
Y
Y
X-Y
Z
S1
S2
D
Fig K-1 Special case
The following conditions are assumed as shown in Fig.K-1.
• The three terminals, A, B and C, and the two T-connected transmission lines
are assumed to be live.
• Terminal C is connected to load only.
• Line 2 CB at terminal A is open.