Threshold supervision
The threshold monitoring checks selected measured values for overshoot or undershoot of an adjustable
threshold. The processing speed of this function is so high that it can be used for protection applications. The
necessary logical combinations can be implemented by means of CFC.
Applications
•
For high-speed monitorings, automatic functions and application-specific protection functions.
•
Together with direct coupling functions with time delay can be said, which also open a fault condition
and a fault record.
•
Application as a simple two-point controller is possible by extending from a smaller stage and a larger
stage an admissible range for these measures values. On exiting this range the particular indication is
issued which then can instigate a corresponding reaction in the process.
Functional Description
Measured Values
There are 6 threshold supervision blocks, 3 each for overshoot and undershoot of the threshold. As result a
logical indication is output that can be further processed by the CFC.
The voltage values of the 6 inputs of the device are available as measured values for threshold monitoring.
Just as the protection functions, the threshold monitoring is also always active. Outside the frequency correc-
tion range (0.5· f
N
to 1.5· f
N
) undervoltage functions tend to overreact, all the functions on the other hand to
underreact.
The following figure shows an overview of the threshold monitoring logic.
[logik-ve6-schwellwert-210303-kn, 1, en_GB]
Figure 2-47 Logic of the Threshold Supervision
The figure shows that the measured values can be freely allocated to the threshold supervision blocks. The
dropout ratio for the MVx> stages is 0.95 or 1 %. Accordingly, it is 1.05 or 1 % for the MVx< stages.
2.9
2.9.1
Functions
2.9 Threshold supervision
SIPROTEC 4, 7VE61 and 7VE63, Manual 101
C53000-G1176-C163-3, Edition 10.2017
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