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Introduction
1.1 Overall Operation
1.1
Overall Operation
The digital SIPROTEC 7SD80 overcurrent protection is equipped with a powerful microprocessor. It allows all
tasks to be processed digitally, from the acquisition of measured quantities to sending commands to circuit
breakers.
Figure 1-1
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 4 current
transformers and - depending on the model - additionally 3 voltage transformers. Three current inputs serve
for the input of the phase currents, another current input (Ι
current Ι
(current transformer starpoint) or for a separate ground current transformer (for sensitive ground
N
fault detection Ι
[hw-struktur-7sd80-100801, 1, en_US]
Figure 1-1
There is one voltage input available for each phase-to-ground voltage. The differential protection does not
need measuring voltages due to its functional principle. Directional overcurrent protection, however, requires
the phase-to-ground voltage V
displaying voltages and power values and also measuring the line voltage for automatic reclosing. The analog
quantities are forwarded to the input amplifier group (IA).
The input amplifier group IA provides high-resistance termination for the analog input quantities. It consists of
filters that are optimized for measured value processing with regard to bandwidth and processing speed.
20
shows the basic structure of the 7SD80 device.
and directional determination of ground faults) - depending on the model.
Ns
Hardware structure of the 7SD80 differential protection
, V
and V
to be connected. Additionally, voltages can be connected that allow
A
B
C
) may be used for measuring the ground fault
N
SIPROTEC 4, 7SD80, Manual
E50417-G1100-C474-A2, Edition 02.2018
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