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SIF5600 - Manual - 03 - 2008
5.5 eLectrIcAL cONNectIONS
electrical connections should be made by referring to the connection diagram on the side of the ap-
paratus; in cases where certain of the circuits (communication, block, or others) are not used, the
relevant connections must remain open.
examples of connection diagrams are reported in Appendix A2 to this manual.
A protective ground connection is required, which must be connected to the suitable screw.
4 mm
2
screw terminals are available for the connections, the use of terminals is recommended.
terminal configuration is shown in the drawings relating to the type of mounting (protruding or re-
cessed).
Since there are no automatic short-circuiting devices present on the connectors to which the cur-
rent transformer secondary connections must be abutted, these must be installed at the same time
as the SIF5600 protective relay. In the case of replacement of the relay, or testing of the current
circuits it is absolutely indispensable to provide suitable back-up terminals for performing short-
circuiting of the secondary. For reasons of safety it is recommended to operate in the absence of
on-line current.
the toroidal transformer used for measuring residual current must be crossed in the same direction
by all active conductors and hence, also by the neutral conductor if distributed, with the exception
of the ground connection protective conductor. the drawing below shows cases of assembly of the
toroid on un-screened and screened cables; prior to proceeding with assembly, it is necessary to
check that there are no screen-to-ground connections upstream of the sensor.
In order to ensure a linear response from the sensor, the conductors must be positioned in the centre
of the toroid so that the magnetic effect of the three cables is perfectly compensated in the absence
of residual current.
Hence, the assembly indicated in the drawing below, in which phase L3 causes local magnetic satu-
ration whereby the vectorial sum of the three currents would be non-null, should be avoided.
the same considerations also apply when the sensor is positioned near bends in the cabling.
It is recommended that the toroid be placed away from bends in the conductors.
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