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6 F 2 S 0 8 5 7
3REF-5.
1REF-1
[
1REF1
]
&
1REF-2
1REF-3
1REF-4
1REF-5
+
T1REF
0.00 - 10.00s
t 0
1REF
71
1REF TRIP
≥1
[
1REF2
]
&
+
[
1REF3
]
&
+
[
1REF4
]
&
+
[
1REF5
]
&
+
332
Same as above
74
2REF-1
2REF-2
2REF-3
2REF-4
2REF-5
2REF
2REF TRIP
≥1
333
Same as above
77
3REF-1
3REF-2
3REF-3
3REF-4
3REF-5
3REF
3REF TRIP
≥1
334
“ON”
“ON”
“ON”
“ON”
“ON”
Note: Models 203 and 204 are not provided with 1REF-4, 1REF-5, 2REF-4, 2REF-5, 3REF-4 and
3REF-5.
Figure 2.3.3 Scheme Logic of Restricted Earth Fault Protection
Appendix L shows applications of the three REF elements to various types of transformers. When
protecting a two- or three-winding transformer, 1REF, 2REF and 3REF elements should be
applied to the primary (or high-voltage) winding, secondary (or medium-voltage) winding and
tertiary (or low-voltage) winding respectively. This is also valid for auto-transformer protection
but the application must comply with Appendix L.
In the application to auto-transformers, one REF element may introduce two or three line currents
and one neutral current as shown in Appendix L. 1REF to 3REF elements recognize the number of
the line currents according to the scheme switch setting of [1REF] to [3REF].