Logic
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Figure 8-16
Logic Diagram of the Voltage-Sum Supervision
The device measures the phase-to-ground voltage and the ground voltage of the lines to be protected. The
sum of the 4 voltages must be 0.
Threshold
If the calculated fault voltage (V
F
) exceeds the Threshold, the parameter Delay failure indication
triggers the indication Failure.
The device calculates the fault voltage (V
F
) with the formula:
VF = |
VA+ VB + VC + Vph/VN • VN |, where Vph/VN forms the Matching ratio Vph / VN parameter.
The Matching ratio Vph / VN parameter takes into account the differing transformation ratios between
the residual voltage input and the phase-voltage inputs.
You can find more information in this respect in chapter 8.3.6.1 Overview of Functions ).
Delay failure indication
When the threshold value for the delay of the failure indication (parameter: Delay failure indication)
is exceeded, the indication Failure is generated.
Blocking the Function
The following blockings reset the picked up function completely:
•
Externally or internally via the binary input signal
>Block function
•
A protection pickup
The pickup signal of a protection function blocks the
Failure
indication.
Supervision Functions
8.3 Supervision of the Secondary System
956 SIPROTEC 5, High-Voltage Bay Controller, Manual
C53000-G5040-C015-9, Edition 11.2017
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