Arcteq AQ-F210, Инструкция по эксплуатации

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Instruction manual –AQ F210 Feeder Protection IED 115 (292
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earth faults. For this purpose restricted earth fault function is stabile since it monitors only
the side it is wired to and compares the calculated and measured residual currents. In case
of outside earth fault the circulating residual current in the faulty phase winding is not
causing tripping because the comparison of measured starpoint current and calculated
residual current differential is close to zero.
Figure 4.2.7.3-41 Restricted earth fault on outside of Y winding transformer.
If the fault is located inside of the transformer and thus inside of the protection area the REF
function catches the fault with high sensitivity since the measured residual current directions
are now opposite for the outside fault situation the measured differential current is high.
Figure 4.2.7.3-42 Restricted earth fault on inside of Y winding transformer.
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