[lo_7SR5_FunctionalTestsLogicDiagram1, 1, en_US]
Figure 9-1 Polarity Testing, Example with Current Transformers Configured in a Holmgreen-Connection
and VTs with Broken-Delta Connection
[lo_7SR5_FunctionalTestsLogicDiagram2, 1, en_US]
Figure 9-2 Polarity Testing, Example with Current Transformers Configured in a Holmgreen-Connection
and VTs with Star Connection
Directional Testing for Isolated or Resonant-Earthed Systems
Primary Test
The most reliable test is by application of a primary earth fault. This is usually practical on these types of
networks due to the low fault currents involved. The primary test is used to provide a definitive evaluation of
the correct polarity of the transformer connections for the determination of the earth fault direction.
Functional Tests
9.5 Direction Test of the Earth Quantities for Directional Earth-Fault Functions
Reyrolle 7SR5, Transformer Protection Device, Device Manual 411
C53000-G7040-C015-1, Edition 11.2019
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