Toshiba GR200 Series Instruction Manual page 439

Detection of current change (OCD)
2.27.5
Current change detection relay
(i)
Suppose that the difference exists between the latest current vector (I
vector (I ). The OCD function will operate if the difference is larger than the setting. The I
N
measured for the last two-cycles; the difference is decided using Equation (2.27-1):
where a criteria for the decision is given by the pick-up threshold value (I s ).
The pick-up threshold is defined using setting [OCD], which is from 0.05 A to 0.20 A at 1 A
rating†. At 5 A rating, 0.25 A to 1.00 A is applied.
OCD logic
(ii)
Figure 2.27-5 shows the OCD logic and its output signals.
A
OCD
B
C
Figure 2.27-5 Scheme logic for current change check
| ��
− ��
��
I
M
I
N
Figure 2.27-4 Current change detection
8000001B66
8100001B67
8200001B68
- 418 -
| > ��
�� ��
I
S
To Common of DISCAR, DEFCAR
8000001B6F
0 t
8100001B70
0 t
8200001B71
0 t
0.1s
6F2S1915 (0.46)
) and the last current
M
is
N
(2.27-1)
To VTF
OCD-A
OCD-B
OCD-C
(2.84.4)
GRZ200 (Soft 031 & 032)