Toshiba GR200 Series Instruction Manual page 124

�� = lagging angle of I to Vp
θ = directional angle setting
Quad element
For the element for the fault in phase-bc, the polarizing voltage (Vp bc ) is given using
Equation (2.10-29):
����
����
For the element for the fault in phase-a, the polarizing voltage (Vp a ) is given using
Equation (2.10-30):
����
where,
V 0 = voltage in zero-sequence
Va = voltage in phase-A
Vbc = voltage in phase-bc
In Equation (2.10-29), the Vp bc voltage is subject to the memory action if the close-in
fault occurs in three-phases; that is, the values of the Va and Vbc voltages are set from the pre-
fault voltages. The memory is retained for two cycles after the fault occurs. Note that the
polarizing voltage (Vpa) in Equation (2.10-30) is not subject to the memory action.
If a close-in fault in three-phases occurs, the Quad element can be enhanced for an offset
Quad element, as shown in Figure 2.10-10. Similar to issuing the instantaneous trip signal for
the close-in three-phase fault, this enables the Quad element to issue a trip signal with a
delayed time together using the memory action.
X
lagging
o
Figure 2.10-9 Directional element
= √3 × ( ���� − �� ) ∠ − 90° + ��
0
= √3 × ( ���� − �� ) + ��
�� 0
- 101 -
I
θ
Directional element
����
∠90°
����
6F2S1914 (0.49)
R
(2.10-29)
(2.10-30)
GRL200 (Soft 033 & 037)