core balance current transformers should have a transformation ratio of at least 70:1.
Lower transformation ratios such as 50:1 or 50:5 are not recommended.
Attention should be paid to make sure the measuring transformers are connected
correctly so that DEFxPDEF is able to detect the fault current direction without
failure. As directional earth fault uses residual current and residual voltage (-U
0
), the
poles of the measuring transformers must match each other and also the fault current
direction. Also the earthing of the cable sheath must be taken into notice when using
core balance current transformers. The following figure describes how measuring
transformers can be connected to the IED.
A070697 V2 EN
Figure 75: Connection of measuring transformers
5.2.3 Transient/intermittent earth-fault protection INTRPTEF
5.2.3.1 Identification
Table 65: Function identification
IEC 61850 identification:
INTRPTEF
IEC 60617 identification: I0> ->IEF
ANSI/IEEE C37.2 device number: 67NIEF
Section 5 1MRS756378 D
Protection functions
154 REF615
Application Manual
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