Siemens SIPROTEC 7SA522 Manual page 154

2 Functions
Figure 2-64 Logic diagram of the 3I
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time delay is calculated here based on the type of the set characteristic, the intensity
of the earth current and a time multiplier ,S 7LPH 'LDO (IEC characteristic, Figure
2-64) or a time multiplier 7LPH'LDO 7',S (ANSI characteristic). A pre-selection of
the available characteristics was already done during the configuration of the protec-
tion functions. Furthermore, an additional fixed delay $GG7'(/$< may be selected.
The characteristics are shown in the Technical Data.
Fig. 2-64 shows the logic diagram. The setting addresses of the IEC characteristics
are shown by way of an example. In the setting information the different setting ad-
dresses are described in detail.
It is also possible to implement this stage equally with a definite time delay. In this
case ,S 3,&.83 is the pickup threshold and $GG7'(/$< the definite time delay.
The inverse time characteristic is then effectively bypassed.
–stage (inverse time overcurrent protection), example for IEC characteristics
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7SA522 Manual
C53000-G1176-C155-3