Toshiba GR200 Series Instruction Manual page 50

The characteristic A and B both are expressed using the following equations:
Y = ( β − α ) × setting [ DIFL-I2 ] − (1 − α) × setting[DIFL-I1]
Equation (2.2-1) and (2.2-2) shows the characteristic A and B, respectively. The user can
set minimum internal fault current using setting [DIFL-I1]. The user can set the knee, which
is referred as crossing point characteristic A and B, using setting [DIFL-I2]. Restraint settings
of the characteristic A and B in percentage are available using settings [DIFL-Slope1] and
[DIFL-Slope2].
Characteristic of Inflowing and Outflowing currents plane
(ii)
Figure 2.2-2 provides another expression corresponding to the Figure 2.2-1; the characteristic
is expressed on the plane between the outflowing current (I out ) axis and inflowing current (I in )
axis. Regarding to the I out –I in plain, the DIF operation is performed in the hatched area of
this figure.
I out
Y / (1 + β)
Figure 2.2-2 Segregated-phase current differential element (I in -I out Plane)
�� ≥ α × ��
��
�� ≥ β × ��
��
X = ( 1 − α ) × setting[DIFL-I1]
setting [ DIFL-Slope1 ]
α =
100
setting [ DIFL-Slope2 ]
β =
100
o
X
1−α
- 27 -
+ X
��
− Y
��
6F2S1914 (0.49)
(2.2-1)
(2.2-2)
(2.2-3)
(2.2-4)
(2.2-5)
(2.2-6)
I in
GRL200 (Soft 033 & 037)