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care should be taken when determining R2, as this is dependent on the method used to connect the
CTs (E.g. residual connection, core balanced CT connection, etc).
2.1.8.3 Sensitive Earth Fault Protection
A core balance CT should be applied, with a minimum knee point calculated as described above.
2.1.8.4 Restricted Earth Fault Protection
High accuracy CTs should be selected with a knee point voltage Vk chosen according to the
equation:
≥ 2× V
V
k
s
where Vs is the differential stability voltage setting for the scheme.
⎯
⎯
73
6 F 2 S 0 8 4 2
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