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SIF5600 - Manual - 03 - 2008
4 F U N C T I O N P R I N C I P L E
4.1 HArDWAre
the hardware structure shown below illustrates the important blocks making up the SIF5600 relay.
the circuits are arranged on two printed circuit boards in accordance with the modular criterion for
the sub-division of the main functions
Power supply board
the circuit board comprises all the components necessary for conversion and stabilization func-
tions.
two versions are envisaged suited to the input ranges 24...48 V and 115...230 V.
the circuit provides stabilized voltages of +10 V and -10 V, required for the analogue measurement
and control circuits, and +3.3 V for supplying the digital circuits.
the circuit board additionally comprises:
INPUt cIrcUItS:
- two or three current transformers for the measurement of the phase currents;
- one current transformer for measuring the residual current;
- two logical input circuits for sampling the status of the breaker;
- one block input circuit (Blin1).
the input circuits have appropriate capacity in order to withstand the current values that may be
present during faults, both permanently and transiently.
the logical input circuits and the block circuits include photo-couplers which provide for galvanic
separation.
OUtPUt cIrcUItS:
- block output circuits (Blout1, Blout2).
the two block output circuits are separated so as to keep the different cabin auxiliary power supply
circuits isolated when connections are made by pilot wire
Processing board
this circuit board contains all the circuits necessary for performing the analogue processing of the
signals so as to allow the microcontroller to achieve the required performances in terms of speed of
execution and measurement precision. Particularly, the following are envisaged:
- antialiasing filter circuits;
- amplifier circuits for conditioning the input signals;
- reference voltage adjustment circuits for the measurement A/D converter.
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