Restricted Earth Fault Protection
In addition to the protection setting and the correct routing of the signals, the polarity connection of current
transformers is important and must be tested for proper system integration.
A single phase primary injection test is the preferred method to prove that the earth point current transformer
is polarity connection is correct. Inspection of connection markings is possible but may not be totally conclu-
sive. The high impedance resistor should be short circuited to reduce the driving voltage requirements of the
test equipment. The REF spill current should be measured at the relay and should be an order of magnitude
less than the relay setting.
[lo_7SR5_FunctionalTestsLogicDiagram9, 1, en_US]
Figure 9-9
Test with High-Current Test Equipment
9.9
Functional Tests
9.9 Restricted Earth Fault Protection
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Reyrolle 7SR5, Transformer Protection Device, Device Manual
C53000-G7040-C015-1, Edition 11.2019