Toshiba GR200 Series Instruction Manual page 382

Fail safe (FS)
Various protection functions are connected to trip function, which opens circuit breakers. The
operation of the trip function should be reliable enough to function correctly, for which the
function of fail-safe (FS) is provided. The Fail safe function includes overcurrent element
(OCFS), phase current change detector element (OCDFS), earth fault element (EFF), multi-
level overcurrent element (OCMF), under-voltage element for phase-to-ground (UVF), under-
voltage element for phase-to-phase fault (UVSF), and under-voltage change detection element
(UVDF). Each element has a scheme switch, and the scheme switch disables the element
independently. As a rule, the FS uses the OCFS. However, for the function of out of step
tripping (OST), the FS can use the OCMF. The OST is discussed separately. (See Chapter Relay
application: Out of step tripping
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Note: Several IED models do not have fail-safe features. To determine whether the features
are implemented in the IED or not, 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 2.29-1 Comparative table in respective ordering numbers
Fail-safe function (FS)
FS
✓: Applicable
)
.
feature
NA: Not applicable
- 359 -
6F2S1914 (0.49)
(2.60.0)
Ordering No. at "G&T"
33 37
✓ ✓
GRL200 (Soft 033 & 037)