Overall Operation - Siemens siprotec SJ62 User Manual

1 Introduction
1.1

Overall Operation

Analog Inputs
21
The SIPROTEC 7SJ62/63/64 are numerical, multi-functional, protective and control
devices equipped with a powerful microprocessor. All tasks are processed digitally ex-
clusively, from acquisition of measured values up to commands to the circuit breakers.
Figure 1-1 illustrates the basic structure of the devices 7SJ62/63, Figure 1-2 illustrates
the basic structure of the device 7SJ64.
The measuring inputs (MI) convert the currents and voltages coming from the instru-
ment transformers and adapt them to the level appropriate for the internal processing
of the device. The device provides four current inputs. Depending on the model, the
device is also equipped with three or four voltage inputs. Three current inputs serve
for input of the phase currents. Depending on the model, the fourth current input (I
may be used for measuring the ground fault current I
or for a separate ground current transformer (for sensitive ground fault detection I
and directional determination of ground faults).
Figure 1-1 Hardware structure of the numerical multi-functional protection device 7SJ62
and 7SJ63
(current transformer starpoint)
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SIPROTEC 4, 7SJ62/63/64 Handbuch
C53000-G1140-C147-A, Edition 07.2015
)
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