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SIF5600 - Manual - 03 - 2008
When making the current connections, attention must be paid to not exceeding the performance of
the line current transformers. to be exact, the total load, constituted by the SIF5600 protective relay,
any other protective relays or measuring instruments and the resistance of the connections, must
not exceed the line ct performance. In particular, consumption of the SIF5600 relay input circuit
must not exceed 0.2 VA while the load (expressed in VA) constituted by the conductors is given by:
0.018 × L ×
I
n
2
/ S
where:
L the overall length, expressed in m, of the two conductors in relation to each phase;
I
n
nominal current of the line ct expressed in A;
S cross sectional area of the current conductors expressed in mm
2
.
In the particular case of the installation of a three-phase version (SIF5600-3Bx-0) on a system with
only two phase current transformers, it is necessary to observe the polarity since current IL3 is
deduced vectorially from the measurement of phase currents IL1 and IL2 (example illustrated in
Appendix 2).
It is recommended that cabling of a suitable thickness be used in order to limit wear of the ct sec-
ondary circuits.
the digital input circuits, despite being galvanically isolated, must preferably be supplied with the
same auxiliary voltage present in the control panel. connections to the breaker auxiliary contacts
(52b and 52a) must be made using two screened conductors and the screening must be connected
to ground.
Block circuit connections must be made with a screened twisted pair cable; screening must be con-
nected to ground only at the end terminating at a protective device block input (further details are
illustrated in the application notes).
Block circuits may be connected to equipment located in a different cabinet: For reasons of reliabil-
ity, it is recommended to use conductors having a cross sectional thickness of at least 1 mm2 and to
not exceed 5 km in length. For connections that are particularly critical in terms of electromagnetic
pollution, it is recommended to use BFO adaptor modules with fibre optic connections.
rS485 communication circuit connections must be made using screened twisted pair cable observ-
ing the polarities shown in the diagrams; screening must only be connected to the end terminating at
the rS485 interface circuit pertaining to the monitoring unit.
It is recommended to terminate the line at the extremities of the same; this must be performed on
the rS485 line control unit and on the SIF5600 device placed at the furthest point connecting the
specially provided resistor.
termination resistors allow adjusting the impedance of the line, reducing the influence of the induc-
tive components of the same, which might compromise good communication.
For connections which are particularly critical in terms of length and electromagnetic pollution, it
might be necessary to insert both the above mentioned termination resistors and so-called Fail Safe
resistors in terminal positions on the line.
In relation to the output contacts, it is necessary to consider that the connection diagram represents
the condition of an unsupplied relay.
CAUTION
The current input circuits do not have any automatic short-circuit devices for the current
transformer secondary circuits, consequently it is necessary to avoid disconnecting such
connections prior to performing an externally short-circuiting.
CAUTION
The current input circuits do not have any automatic short-circuit devices for the current
transformer secondary circuits, consequently it is necessary to avoid disconnecting such
connections prior to performing an externally short-circuiting.