Toshiba GR200 Series Instruction Manual page 1725

=
n '
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 load current
Lmax
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.
S1
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.
+
2
R / I R

VA n ct
n
+
R R
2 ct
Terminal A
Line 2
D
Line 1
X
Y
Terminal C
Fig K-1 Special case
- 1702 -
(K-1)
Terminal B
Y
S2
Y
X-Y
Z
Y
6F2S1914 (0.49)
GRL200 (Soft 033 & 037)