The default setting is a reasonable compromise between measuring accuracy and pickup time. For a non-
sensitive setting (high threshold value), you can set the parameter Measuring window to a smaller value.
Stage Description
Description
Logic of the Stage
[lodfdtst-160113-01.tif, 1, en_US]
Figure 6-221
Logic Diagram of Rate of Frequency Change Protection
(1) For the stage type df/dt rising, the value df/dt rising is used.
Frequency Rising/Falling
The stage df/dt falling is used to detect frequency falling and the stage df/dt rising is used to detect
frequency rising.
You set the threshold value as an absolute value. You define the frequency-change direction via the selected
stage type.
Blocking of the Stage
The following blockings reset the picked up stage completely:
•
Via the binary input signal
>Block stage
•
Via the undervoltage blocking when the voltage drops below the Minimum voltage
6.35.4
6.35.4.1
Protection and Automation Functions
6.35 Rate of Frequency Change Protection
SIPROTEC 5, Overcurrent Protection, Manual 787
C53000-G5040-C017-8, Edition 07.2017
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