Siemens SIPROTEC Manual page 219

Figure 2-104 Logic diagram of the 3I
Definite time high set current stage 3I
The logic of the high-set current stage 3I
must merely be replaced with 3I0>>. In all other respects Figure 2-104 applies.
Definite time overcurrent stage 3I
The logic of the overcurrent stage 3I
must merely be replaced with 3I0>. In all other respects Figure 2-104 applies. This stage operates with a spe-
cially optimized digital filter that completely suppresses all harmonic components beginning with the 2nd har-
monic. Therefore it is particularly suited for a highly-sensitive earth fault detection.
A fourth definite-time stage can be implemented by setting the „inverse-time" stage (refer to the next paragraph)
to definite-time stage.
SIPROTEC, 7SD5, Manual
C53000-G1176-C169-5, Release date 02.2011
>>> stage
0
>>
0
>> is the same as that of the 3I
0
>
0
>, too, is the same as that of the 3I
0
2.8 Earth Fault Protection in Earthed Systems (optional)
>>> stage. In all references 3I0>>>
0
>>> stage. In all references 3I0>>>
0
Functions
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