Toshiba GR200 Series - 2.17 Negative sequence overcurrent protection (OCN)

6F2S1914 (0.49)
GRL200 (Soft 033 & 037)
- 261 -
Negative sequence overcurrent protection (OCN)
Negative-sequence overcurrent protection (OCN) function has both time characteristic and
directional elements. Four stages (elements) are available in the OCN function. The user can
select various features using the scheme switches provided. The elements are named OCN1,
OCN2, and others; and they operate independently.
To simplify the description, only OCN1 is discussed but is applicable to the other OCNs;
hence, read the expression for OCN1 as OCN2, OCN3, and OCN4 at each stage unless a special
explanation or instruction has been provided.
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Note: The number of relay elements depends on the IED model. To know the number in
respective IED models, locate the IED ordering number; and check the order number at “G&T
position” referring to the comparison table below. For more information, see Appendix:
Ordering .
Table 2.17-1 Comparative table in respective ordering numbers
No. of stages
Ordering No. at “G&T”
33
37
Non-Directional / directional NOC protection
4
✓
✓
✓: Applicable NA: Not applicable