Functions
2.16 Backup Time Overcurrent Protection
SIPROTEC, 7SD5, Manual
C53000-G1176-C169-5, Release date 02.2011
306
Additional Stage I>>>
An additional overcurrent stage I>>> has an additional enable input (figure 2-155). It is therefore also suitable
as an emergency stage, for instance. The enable input „>I-STUB ENABLE“ can be assigned to the output
signal „Emer. mode“ (either via binary outputs and inputs or via the user-definable CFC logic functions). The
stage is then automatically active as soon as the differential protection is not effective due to a communication
disturbance, and the distance protection is not effective due to a failure of the measuring voltage.
The I>>> stage can, however, also be used as a standard additional and independent overcurrent stage, since
it works independent of the other stages. In this case, the enable input „>I-STUB ENABLE“ must be activated
permanently (via a binary input or CFC).
Figure 2-155 Logic diagram of the I>>> stage
1
) Output indications associated with the pickup signals are listed in Table 2-12
2
) Output indications associated with the trip signals are listed in Table 2-13
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