Toshiba GR200 Series Instruction Manual page 415

Calculation error
(iv)
User should note that the calculation error could be larger when a setting value is far from
actual line impedance. For example, if abnormal settings
be appeared notably.
The calculation error can be with in ± 2.5 km when the following conditions are applied:
A fault is assumed to arise up to 100 km distance.
⚫
The fault current is larger than double of the rated current
⚫
The reactance
⚫ 3
In other words, this calculation error can be with in ±2.5% when the following conditions
are applied:
The line length (L) is shorter than 100km.
⚫
The reactance per unit length ( X1 L ⁄ ) is larger than a value ( 0.05 I
⚫
The fault current is larger than double of the rated current
⚫
Note: Abnormal settings can be exist when values are far from actual impedance data of
1
transmission line. For example, resistance value is so larger then reactance value,
and so on.
Note: Rated current (In) is described separately. (See Chapter
2
Transformer module
Note: The term X1 is the reactance component of line impedance.
3
Selection of calculation results
2.32.3
At the outset, we discuss that the FL calculation consist of two groups: (1) FL calculation with
data at a local-terminal and remote-terminals and (2) FL calculation with data at a local-
terminal only. Hence, either (1) or (2) is selected as a calculation result in accordance with a
fault condition. The FL selects the result of (2) FL calculation with data at a local-terminal
only when the FL finds the following conditions after the calculations:
The calculation results are less than 20% of the line length (L).
⚫
The result difference between (1) and (2) is within 5% of the line length (L).
⚫
The calculation result is less than 40km.
⚫
per unit length ( X1 L ⁄ ) is longer than a value ( 0.05 I
)
- 392 -
6F2S1914 (0.49)
are done, the calculation error will
1
(2 × I ).
2
n
⁄ ).
n
⁄ ).
n
(2 × I ).
2
n
Technical description:
GRL200 (Soft 033 & 037)