Overall Operation
The numerical SIPROTEC 7SJ62/64 multifunction protection devices are equipped with a powerful microproc-
essor. It allows all tasks to be processed digitally, from the acquisition of measured quantities to sending
commands to circuit breakers. Figure 1-1 and Figure 1-2 illustrate the basic structure of the devices 7SJ62 and
7SJ64.
Analog Inputs
The measuring inputs (MI) convert the currents and voltages coming from the instrument 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 (Ι
N
) may be
used for measuring the ground fault current Ι
N
(current transformer neutral point) or for a separate ground
current transformer (for sensitive ground fault detection Ι
Ns
and directional determination of ground faults).
[hw-struktur-7sj62-63-110602-kn, 1, en_US]
Figure 1-1
Hardware structure of the numerical multi-functional device 7SJ621/622
Voltage inputs can either be used to measure the three phase-to-ground voltages, or two phase-to-phase
voltages and the displacement voltage (V
N
voltage). It is also possible to connect two phase-to-phase voltages
in open-delta connection.
The 4 voltage transformers of 7SJ623, 7SJ624, 7SJ625, 7SJ626 and 7SJ64 can either be applied for the input
of 3 phase-to-ground voltages, one displacement voltage V
0
or a further voltage for the synchronization func-
tion.
1.1
Introduction
1.1 Overall Operation
20 SIPROTEC 4, 7SJ62/64, Manual
C53000-G1140-C207-8, Edition 08.2016
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