Toshiba GR200 Series Instruction Manual page 56

switch [DIFLFS-EN] when the operation of the check relays is required to operate for the DIFL
function.
Current change detection element (OCD-DIFL)
(i)
Figure 2.2-5 shows a current vector (I M ) measured at the present and a pre-current vector (I N )
measured at one sampling cycle† ago. When the magnitude of difference between (I s ) is larger
than a setting, the OCD-DIFL element is operated. The OCD-DIFL element is expressed by
the following equation:
where I s is referred in order to determine the operation of the OCD-DIFL element; the
user can set the value using setting [OCD-DIFL], which is applied to adjust the decision point
for the operation. The user can set the value among 0.05 to 0.20A when 1A rating‡ is applied
for the VCT module. When 5A rating‡ is applied for the VCT module, the setting value is
chosen among 0.25 to 1.00A.
The quiescent load current does not affect the sensitivity of the OCD-DIFL element; thus,
the OCD-DIFL element can detect a fault current sensitively.
Figure 2.2-5 Current change I s detected by I M and I N
†Note: We define a sampling cycle as 7.5 electrical degrees.
‡Note: For the rating and the VCT module, see Chapter
Transformer module for AC analog input
Over-current detection (OC-DIFL)
(ii)
For OC-DIFL relay element the user can set the sensitivity using setting [OC-DIFL]. When 1A
rating, OC-DIFL value is selected from 0.05 to 50.00A. When 5A rating, the setting value is
placed from 0.10 to 250.00A.
Under-voltage element (UV-DIFL)
(iii)
For UV-DIFL relay element the user can set the sensitivity using setting [UV-DIFL]. The value
is selected from 5.0 to 130.0 V.
| �� | > ��
− ��
�� �� ��
I N
I s
I M
.
- 33 -
6F2S1914 (0.49)
(2.2-9)
Technical description:
GRL200 (Soft 033 & 037)